Regional variations in childbirth interventions in the Netherlands: a nationwide explorative study

Regional variations in childbirth interventions in the Netherlands: a nationwide explorative study Background: Although interventions in childbirth are important in order to prevent neonatal and maternal morbidity and mortality, non-indicated use may cause avoidable harm. Regional variations in intervention rates, which cannot be explained by maternal characteristics, may indicate over- and underuse. The aim of this study is to explore regional variations in childbirth interventions in the Netherlands and their associations with interventions and adverse outcomes, controlled for maternal characteristics. Methods: Childbirth intervention rates were compared between twelve Dutch regions, using data from the national perinatal birth register for 2010–2013. All single childbirths from 37 weeks’ gestation onwards were included. Primary outcomes were induction and augmentation of labour, pain medication, instrumental birth, caesarean section (prelabour, intrapartum) and paediatric involvement. Secondary outcomes were adverse neonatal and maternal outcomes. Multivariable logistic regression analyses were used to adjust for maternal characteristics. Associations were expressed in Spearman’s rank correlation coefficients. Results: Most variation was found for type of pain medication and paediatric involvement. Epidural analgesia rates varied from between 12 and 38% (nulliparous) and from between 5 and 14% (multiparous women). These rates were negatively correlated with rates of other pharmacological pain relief, which varied from between 15 and 43% (nulliparous) and from between 10 and 27% (multiparous). Rates of paediatric involvement varied from between 37 and 60% (nulliparous) and from between 26 and 43% (multiparous). For instrumental vaginal births, rates varied from between 16 and 19% (nulliparous) and from between 3 and 4% (multiparous). For intrapartum caesarean section, the variation was 13–15% and 5–6%, respectively. A positive correlation was found between intervention rates in midwife- led and obstetrician-led care at the onset of labour within the same region. Adverse neonatal and maternal outcomes were not lower in regions with higher intervention rates. Higher augmentation of labour rates correlated with higher rates of severe postpartum haemorrhage. Conclusions: Most variation was found for type of pain medication and paediatric involvement, and least for instrumental vaginal births and intrapartum caesarean sections. Care providers and policy makers should critically audit remarkable variations, since these may be unwarranted. Limited variation for some interventions may indicate consensus for their use. Further research should focus on variations in evidence-based interventions and indications for the use of interventions in childbirth. Keywords: Childbirth, Interventions, Obstetric, Regional, Variations, Outcomes, Caesarean section, Induction, Pain relief * Correspondence: a.seijmonsbergen@vumc.nl Department of Midwifery Science, AVAG, Amsterdam Public Health research Institute, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, the Netherlands Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 2 of 18 Background led care in the Netherlands, and controlled for maternal The rates of interventions in childbirth vary worldwide characteristics. [1–4] and have fluctuated over the years [1, 4–7]. Induc- tion of labour and caesarean section (CS) rates have Methods shown a steady increase since the 1970s [1, 4, 6, 8, 9], Data collection which raised concerns [10]. Interventions in childbirth For this nationwide study, we used consolidated data of are important in order to prevent neonatal and maternal the years 2010 to 2013 from Perined, the national peri- morbidity and mortality. However, use without a medical natal register that includes data from almost all births in indication may cause avoidable harm [2, 11–14]. The the Netherlands. Perined aims to improve the quality of World Health Organization (WHO) recommends lim- perinatal care through providing data for research and ited use of interventions during childbirth [15]. Induc- audits on adverse outcomes. The Perined register in- tion and augmentation of labour should only be cludes data from: primary midwife-led care (the national performed on medical indication [16, 17]. However, perinatal database 1); secondary obstetrician-led care there are concerns about poor adherence to this recom- (the national perinatal database 2); paediatric care (the mendation in a significant number of women with un- national neonatal register); and primary midwifery care complicated pregnancies [16–19]. Epidural analgesia is by general practitioners (the national perinatal database the most effective method for pain medication during h). The data are routinely recorded by the care providers labour [20], but is associated with a higher risk of instru- and combined into the Perined register via a validated mental birth, oxytocin use, maternal fever, urinary reten- linkage method [37, 38]. More than 98% of all midwifery tion and complications, such as post-dural puncture practices and obstetric hospital units record their births headache [20, 21]. The decision for pain medication is in this combined database [39]. All single childbirths ultimately based on women’s choice. There is some evi- from 37 weeks’ gestation onwards were included. Exclu- dence that continuous support of labour might reduce sion criteria were missing data on: postal code; parity; or the need for pain medication [22]. Furthermore, the from the national perinatal database 1, covering WHO states that CS rates higher than 10 % at popula- midwife-led care, but where the woman was referred to tion level are not associated with reductions in maternal, obstetrician-led care, covered by the national database 2. neonatal and infant mortality rates [23]. In the Netherlands, low-risk women in primary Variations in intervention rates between high-income midwife-led care are cared for by independent midwives countries may be explained by culture and history, dif- who attend home births, low-risk hospital births, and ferences in population characteristics, maternity care births in alongside and free-standing birth centres. The systems, and national guidelines [12, 15, 24–26]. Clinical Dutch Birth Centre Study showed that health outcomes, guidelines have been used for a long time to harmonise experiences, and costs for low-risk women are similar and rationalise the use of interventions within countries, for planned birth in a birth centre and planned birth in and to improve outcomes [27, 28]. Nevertheless, studies a hospital, both supervised by a primary care midwife comparing regions within countries like England, [40, 41]. When risks for adverse outcomes increase or Ireland, Canada and Germany, have found substantial complications arise, women are referred to obstetrician- variations in rates of induction of labour, epidural anal- led care. Interventions in childbirth such as induction gesia, continuous fetal electronic monitoring, episiot- and augmentation of labour, pain medication, instru- omy, instrumental birth, and CS [29–33]. Additionally, mental birth, and CS, are only available in an Dutch studies have reported variations in rates between obstetrician-led care setting [42, 43]. Intrapartum inter- hospitals, of induction and augmentation of labour, ad- ventions may be used for women in midwife-led care at ministration of sedation and analgesics, episiotomy, in- the onset of labour after referral to obstetrician-led care. strumental birth, and CS [34, 35]. Regional variations in Therefore, intervention rates are not comparable for intervention rates, which cannot be explained by mater- women who are in midwife-led care and women who nal characteristics, may indicate over- and underuse are in obstetrician-led care at the onset of labour. [36]. This is especially true in a relatively small country The VU University Medical Center confirmed that eth- without regional differences in the maternity healthcare ical approval was not required for this study according to system. the Dutch legislation (reference WC2016–055; http://www. The aim of this study was therefore to explore which ccmo.nl/en/your-research-does-it-fall-under-the-wmo). regional variations in intervention rates in childbirth exist, and how these variations are associated both to each other, and to adverse neonatal and maternal out- Interventions comes. These are explored for single childbirths from Births were attributed to one of the twelve Dutch 37 weeks of gestation onwards in midwife- or obstetrician- administrative provinces (further referred to as ‘regions’) Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 3 of 18 according to the residential postal code of the mother. confounders [29, 30, 32, 46–49]: parity (nulliparous, All low-risk women have access to all types of birth set- multiparous); care setting at the onset of labour (mid- tings, but not all types are present in all regions [44]. wife-led, obstetrician-led), maternal age (< 20, 20–24, We adjusted for this by using the residential postal code 25–29, 30–34, 35–39, ≥40 years); ethnic background of the mother. (Dutch, non-Dutch); degree of urbanisation (urban, The following interventions were examined as the pri- intermediate, rural); socioeconomic status (high, mary outcomes: induction of labour; augmentation after a medium, low); gestational age (37 + 0–37 + 6, 38 + 0–40 spontaneous onset of labour; intrapartum oxytocin use; +6, 41 +0–41 + 6, ≥42 weeks); and birth weight (< 2.3rd, epidural analgesia; other pharmacological pain relief; <10th, >90th, > 97.7th percentile). Ethnic background instrumental vaginal birth; CS (prelabour, intrapartum); was reported by the care provider and was defined as and involvement of a paediatrician in the first 24 h after Dutch or non-Dutch, because of inconsistencies in birth. Births from 42 weeks onwards were not excluded, recording non-Dutch subgroups. The degree of urbanisation because they may explain variation in particularly induc- was based on the four digits of the residential postal code of tion of labour rates, and they may reflect different policies the mother. For 2500 or more addresses/km ,the degree of between regions. Artificial rupture of membranes before a urbanisation was categorized as urban, and for less than 500 spontaneous onset of labour was defined as induction of addresses/km as rural. Socioeconomic status [SES] was labour, and administration of oxytocin to stimulate uterine based on a proxy measure indicated by the Netherlands contractions after spontaneously ruptured membranes as Institute for Social Research (SCP), which includes augmentation. A CS after spontaneously ruptured mem- education, employment, and level of income of the branes was defined as intrapartum CS. Intrapartum oxyto- residential postal code area (Statistics Netherlands; https:// cin includes the use of oxytocin for induction or for bronnen.zorggegevens.nl/Bron?naam=Sociaal-Economische- augmentation of labour, but not oxytocin use in the third Status-per-postcodegebied). SES was classified as high, stage of labour. Women with a prelabour CS were medium and low, based on the 25 and 75 percentile excluded from the analyses on pain medication. Women cut-off points. with an intrapartum CS and an epidural, are classified as epidural analgesia for labour pain, since epidural analgesia is generally not used for caesarean sections without prior Data analysis epidural analgesia for labour pain. In Perined ‘other The baseline characteristics were described in percent- pharmacological pain relief’ is specified as: sedatives; non- ages per region. The variation in interventions was opioid analgesics; and opioid analgesics without further analysed overall, and in subgroups according to the care details. The most common opioid analgesics are pethidine setting. Stratification by parity was applied for the crude injections, sometimes combined with a sedative such as rates. Univariable analyses were performed to gain promethazine, and patient-controlled remifentanil [45]. In insight in the variations of intervention rates and child- some births, epidural analgesia and other pharmacological birth outcomes in the twelve regions. All interventions methods for pain medication were both used, and there- and childbirth outcomes mentioned above were included fore, the percentages could not be added up [45]. in the univariable analyses. The percentages of missing data were low, namely from between 0.0 to 2.5% for Neonatal and maternal outcomes baseline characteristics, from between 0.0 to 0.8% for The secondary neonatal and maternal outcomes were: interventions, from between 0.0 to 0.1% for neonatal antepartum and intrapartum stillbirth; neonatal mortal- outcomes, and from between 1.4 to 2.7% for maternal ity; Apgar score below 7 at 5 min; third or fourth degree outcomes. Therefore, cases with missing data were perineal tear among vaginal births; and postpartum excluded. haemorrhage (PPH) of 1000 ml or more. Antepartum Multivariable logistic regression analyses were con- stillbirths with births beyond 37 weeks were included, ducted for all births and stratified by the care setting, since this may influence intervention rates. Neonatal with adjustments for: parity; maternal age; ethnic back- mortality was defined as neonatal death up to 7 days. ground; socioeconomic position; and the degree of Antepartum and intrapartum stillbirths were excluded urbanisation. The results of the multivariable analyses from the analyses on Apgar score. Women who gave were illustrated in figures with maps and boxplots with birth by CS were excluded from the analyses on third or adjusted odds ratios (ORs) and 99% confidence intervals fourth degree perineal tear. (CIs). The weighted overall intervention rate was taken as the reference. This weighted rate was the overall Maternal and neonatal characteristics intervention rate, with the intervention rate of the The following maternal and neonatal characteristics region weighted for the number of women in each were included as independent variables or potential region. A confidence interval of 99% was chosen to Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 4 of 18 limits chance findings due to multiple testing in a large Statistical analyses were performed using SPSS Statis- dataset. Outcome variables were dichotomised and tics 22 (SPSS Inc., Chicago, IL, USA). dummy variables were created to account for potential First, overall results and remarkable associations be- confounders in the multivariable logistic regression ana- tween subgroups of women or between interventions lyses. An important topic of this study, was to explore were described. Second, results for each intervention whether the variation of one intervention was associated were described, starting with those that showed most with the variation of another intervention. Instead of ex- variation. ploring associations with eyeballing only, we quantified these associations by calculating Spearman’srank correl- Results ation coefficients. These were calculated to demonstrate Baseline characteristics the associations of regional adjusted ORs between inter- Figure 1 shows the number of births eligible for inclusion ventions in different care settings, and between interven- in this study and Table 1 describes the maternal and neo- tions and childbirth outcomes. Correlation coefficients natal characteristics. Of the 276,701 births in nulliparous were calculated for the adjusted ORs of the regions, but women, 153,091 were in midwife-led care at the onset of only for outcomes that varied significantly between the re- labour, 121,612 in obstetrician-led care, and for the gions. Since the sample size for all calculated correlations remainder, the care setting was unknown. For births in was the same, namely 12 regions, all correlations with ρ ≥ multiparous women, these numbers were 174,918 and 0.57 or ≤− 0.57 corresponded with a p-value of 0.05. Al- 161,286 respectively. In the regions, the proportion of though the limits for clinically significant correlations are mothers younger than 20 years of age ranged from be- arbitrary, we considered a correlation of ρ ≥ 0.60 tween 0.8 to 2.2%, and of 40 years or older from between or ≤− 0.60 as strong [50], and only these correlations were 2.4 to 4.5%. The lowest proportion of mothers with a non- discussed in the text and indicated in bold in the tables. Dutch ethnicity was 9.3% and the highest 34.6%. In three Women who gave birth in 2010-2013 Women excluded from the study, in order of n = 703,942 exclusion: - multiple gestation (n=23,376) or missing information (n=613) - birthbefore 37 weeks gestation (only singletons: n=47,700) -missing postcode (n=5,888), parity (n=26) or national perinatal database 1 in case of referral to obstetrician-led care (n=11,609) Women who gave birth to a n = 89,212 single child from 37 weeks gestation onwards n = 614,730 Nulliparous women Multiparous women n = 276,701 n = 338,029 In midwife-led In obstetrician- In midwife-led In obstetrician- care at onset led care at Unknown care at onset led care at Unknown of labour onset of labour n = 1,998 of labour onset of labour n= 1,825 n = 153,091 n = 121,612 n = 174,918 n = 161,286 Fig. 1 Study population Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 5 of 18 Table 1 Maternal and neonatal characteristics of women by region GR FR DR OV FL GD UT NH ZH ZL NB LB Total n 19,441 22,568 15,875 42,869 17,461 71,286 52,893 105,948 139,573 11,327 84,187 31,302 Parity, % Nulliparous 45.8 42.4 42.7 42.1 41.4 43.4 44.7 46.8 45.7 42.8 45.8 47.2 Multiparous 54.2 57.6 57.3 57.9 58.6 56.6 55.3 53.2 54.3 57.2 54.2 52.8 Maternal age, % < 20 years 1.9 1.5 1.6 1.2 2.2 1.2 0.8 1.0 1.5 1.6 1.0 1.6 20–24 years 12.4 11.5 11.6 10.0 13.9 10.0 7.5 8.4 11.7 15.2 8.7 10.6 25–29 years 31.2 34.8 35.4 33.4 33.9 31.6 26.7 26.2 30.3 33.9 31.5 32.2 30–34 years 35.4 35.1 34.2 38.0 32.3 37.5 40.6 38.2 35.6 33.1 39.8 37.8 35–39 years 16.1 14.5 14.7 14.9 14.6 16.6 20.9 21.6 17.4 13.6 16.5 15.2 ≥40 years 2.9 2.7 2.5 2.4 3.0 3.1 3.6 4.5 3.5 2.7 2.5 2.7 Ethnic background, % Dutch 85.7 90.7 89.9 86.2 65.4 85.6 77.5 67.1 65.4 87.2 80.1 82.7 Non-Dutch 14.3 9.3 10.1 13.8 34.6 14.4 22.5 32.9 34.6 12.8 19.9 17.3 Urbanisation, % Urban 18.0 4.6 0.0 2.9 0.0 3.8 23.0 39.8 41.7 0.0 9.0 2.5 Intermediate 49.2 47.0 53.6 71.3 72.5 71.4 59.6 49.1 45.0 53.3 70.0 69.7 Rural 32.9 48.5 46.4 25.9 27.5 24.8 17.4 11.1 13.3 46.7 21.0 27.8 Socioeconomic status, % High (p ≥ 75) 9.3 11.8 19.4 16.9 39.2 19.1 35.7 23.5 25.5 7.4 20.0 8.7 Medium (p 25–75) 31.5 34.8 40.5 51.4 36.8 56.0 38.8 39.0 39.1 60.3 55.8 58.4 Low (p ≤ 25) 59.2 53.4 40.0 31.7 24.1 24.9 25.4 37.5 35.4 32.2 24.1 32.9 Gestational age (weeks), % 37 + 0–37 + 6 8.7 8.3 9.2 8.6 8.4 6.7 5.8 6.6 7.6 6.5 7.3 8.8 38 + 0–40 + 6 71.5 71.7 72.5 72.1 73.1 71.6 71.2 72.2 72.8 71.6 72.4 73.9 41 + 0–41 + 6 17.9 18.1 16.9 17.4 16.9 19.3 20.7 19.0 18.3 19.4 18.5 16.5 ≥42 1.8 1.9 1.4 1.8 1.6 2.3 2.3 2.2 1.4 2.5 1.8 0.8 Birth weight, % < 2,3rd percentile 1.7 1.4 1.4 1.5 1.8 1.6 1.7 1.8 1.9 2.0 2.0 2.1 <10th percentile 8.0 6.8 7.3 7.4 9.5 7.8 7.9 8.4 8.9 8.8 9.3 9.7 >90th percentile 11.3 12.9 11.9 11.0 9.8 11.2 10.6 10.3 9.7 10.0 9.0 9.0 > 97,7th percentile 3.0 3.5 3.4 2.9 2.4 3.0 2.7 2.7 2.5 2.4 2.3 2.4 Percentage of missing data: 0.0% for maternal age, 0.4% for ethnic background, 1.1% for urbanisation, 2.5% for socioeconomic status, 0.2% for birth weight regions, there were no urban areas, whereas in all regions Results on the national level there were mothers living in rural areas, with a range of The greatest variation was found for the type of pain medi- between 11.1 and 48.5%. Proportions of mothers with a low cation and whether a paediatrician was involved within socioeconomic status varied from between 24.1 to 59.2%. 24 h after birth, followed by variation in augmentation after Regions with the lowest number of births after a spontaneous onset of labour. Less variation was found for 42 weeks (varying from between 0.8 to 2.5%), had induction of labour and prelabour CSs, and least for instru- higher numbers of births at 37–38 weeks (varying mental vaginal births and intrapartum CSs (Figs. 2, 3, 4, 5, 6 from between 5.8 to 9.2%), and vice versa. We found and 7). Similar variation in intervention rates was found for a similar pattern for birth weight below the 2.3rd, births in midwife-led care compared to those in 10th or above the 90th or 97.7th percentile, with obstetrician-led care at the onset of labour in the same rates varying from between 1.4 to 2.1% for birth region (Additional file 1: Table S5). The adverse neonatal weight below the 2.3rd percentile, and from between and maternal outcomes were not lower in regions with 2.3 to 3.5% for birth weight above the 97.7th. higher intervention rates (Additional file 1:Table S8). Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 6 of 18 2,9 2,8 = 0.61 - 2,7 2,6 2,5 2,4 2,3 2,2 2,1 1,9 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 GR FR DR OV FL GD UT NH ZH ZL NB LB 2,9 2,8 = 0.68 - 2,7 2,6 2,5 2,4 2,3 2,2 2,1 1,9 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for epidural analgesia with 99% confidence interval Adjusted OR for other pharmacological pain relief with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country (rho) is the coefficient between the two point markers in the figure (epidural analgesia and other pharmacological pain relief), which corresponds with the correlation coefficient described in table 6. Fig. 2 a: Regional variation of epidural analgesia and other pharmacological pain relief for women in midwife-led care. b: Regional variation of epidural analgesia and other pharmacological pain relief for women in obstetrician-led care Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 7 of 18 1,7 = 0.67 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 0,4 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for involvement of a paediatrician <24 hrs among women in midwife- led care with 99% confidence interval Adjusted OR for involvement of a paediatrician <24 hrs among women in obstetrician-led care with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country. (rho) is the coefficient between the two point markers in the figure (paediatric involvement for women in midwife-led versus obstetrician-led care), which corresponds with the correlation coefficient described in table 5. Fig. 3 Regional variation of paediatric involvement for women in midwife-led care and obstetrician-led care Regional variations were no significant correlations between the use of pain Table 2 describes the intervention rates by region in sub- medication and augmentation of labour, intrapartum oxy- groups stratified by parity, and Additional file 2: Table S4 tocin use, instrumental vaginal birth, intrapartum CS, or the crude and adjusted ORs with confidence intervals, on spontaneous vaginal birth (Additional file 1: Table S7). As which Figs. 2, 3, 4, 5, 6 and 7 are based. Most variation can be seen from Fig. 3, considerable variation was found was found for the type of pain medication during labour for the involvement of a paediatrician in the first 24 h after (Fig. 2a and b), with epidural analgesia rates varying from birth, with rates varying from between 36.9 to 60.3% for between 12.3 to 37.5% in nulliparous and from between nulliparous and from between 25.6 to 42.7% for multipar- 4.6 to 13.8% in multiparous women, and rates of other ous women (Table 2). pharmacological pain relief varying from between 14.8 to Figure 4 shows maps with variations of spontaneous 43.0% in nulliparous and from between 9.8 to 26.8% in birth rates, CS rates, and rates of intrapartum oxytocin multiparous women without prelabour CS (Table 2). The between regions. Rates of intrapartum oxytocin, used for variation of pain medication was similar for women in induction or augmentation of labour, were found of midwife-led compared to those in obstetrician-led care between 55.1 and 66.5% for nulliparous and of between within the same region, with ρ =0.97 (Additional file 1: 39.7 and 51.7% for multiparous women (Table 2), and Table S5), but rates were lower for women in midwife-led varied significantly across regions (Fig. 4c). Rates of aug- care. Generally, lower rates of other pharmacological pain mentation after a spontaneous onset of labour varied relief were found in regions with higher rates of epidural across regions from between 33.5 to 48.4% for nullipar- analgesia, and vice versa. The correlation coefficient was ous and from between 12.4 to 22.6% for multiparous ρ = − 0.61 for women in midwife-led care and ρ = − 0.68 in women (Table 2). Instrumental vaginal birth rates were obstetrician-led care (Additional file 1: Table S6). There lower (ρ = − 0.61) and spontaneous vaginal birth rates Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 8 of 18 GR=Groningen; FR=Friesland; DR=Drenthe; OV=Overijssel; FL=Flevoland; GD=Gelderland; UT=Utrecht; NH=Noord-Holland; ZH=Zuid-Holland; ZL=Zeeland; NB=Noord-Brabant; LB=Limburg. Fig. 4 Significant differences in adjusted* OR between regions in incidences of: a. spontaneous births. b. caesarean sections. c. intrapartum oxytocin use. (* Adjusted for parity, maternal age, ethnic background, socioeconomic status and urbanisation) were higher (ρ = 0.66; Additional file 1: Table S7) in re- (nulliparous women) and from between 5.3 to 6.4% gions where rates of augmentation of labour were (multiparous women), and instrumental birth rates higher. Variations in augmentation of labour are shown varied from between 16.2 to 19.4% (nulliparous in Fig. 5. women) and from between 3.1 to 4.2% (multiparous Less variation was found for induction of labour, women) (Table 2). For midwife-led care, regions with instrumental vaginal birth, and prelabour and intra- higher intrapartum CS rates had higher instrumental partum CS. Rates of prelabour CS were found of be- birth rates as well (ρ = 0.60), but this correlation was tween 3.6 and 5.8% for all nulliparous and of between not significant in obstetrician-led care at the onset 5.8 and 9.8% for all multiparous women, and induc- labour (ρ =0.45; Additional file 1: Table S6). For all tion of labour rates of between 18.0 and 26.2% for all nulliparous women, a variation of spontaneous vaginal nulliparous and of between 16.6 and 25.4% for all birth rates was found of between 62.4 and 67.4%, and multiparous women (Table 2). Figure 6 illustrates the for multiparous women, of between 81.7 and 86.1% ORs of prelabour CS and induction of labour. Regions (Table 2). with higher rates of prelabour CS had higher rates of intrapartum CS as well (ρ = 0.67), and lower rates of spontaneous vaginal births (ρ = − 0.62; Additional file 1: Neonatal and maternal outcomes Table S7). The results of the multivariable analyses for the child- Compared to the other interventions, least variation birth outcomes are described in Table 3. The overall was found for intrapartum CS and instrumental vaginal incidence of antepartum and intrapartum stillbirth birth for women without prelabour CS (Fig. 7a and b). was 0.12% and of neonatal mortality up to 7 days 0.08%, Intrapartum CS rates varied from between 12.7 to 15.4% but the adjusted ORs did not vary significantly Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 9 of 18 1,8 = 0.76 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for augmentation of labour women in midwife-led care with 99% confidence interval Adjusted OR for augmentation of labour among women in obstetrician-led care with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country. (rho) is the coefficient between the two point markers in the figure (augmentation of labour for women in midwife-led versus obstetrician-led care), which corresponds with the correlation coefficient described in table 5. Fig. 5 Regional variation of augmentation of labour after spontaneous onset for women in midwife-led care and obstetrician-led care between regions (Table 3;not showninfigures). and for the involvement of a paediatrician in the first Correlation coefficients were therefore not calculated 24 h after birth. Less variation was found for prelabour for these outcomes. The incidence of Apgar score CS, augmentation and induction of labour, and least for below 7 at 5 min varied significantly across regions instrumental vaginal birth and intrapartum CS rates. from between 0.7 to 1.5%. For third and fourth Regions with higher rates of one intervention did not degree perineal tear, incidences varied from between have higher rates of all other interventions. Interventions 1.8 to 3.2% and for PPH from between 3.7 to 6.9%. that were correlated, were epidural analgesia and other The only intervention and adverse outcome that pharmacological pain relief (negatively), augmentation of were significantly correlated, were augmentation of labour and instrumental vaginal birth (negatively), intra- labour after a spontaneous onset of labour and PPH partum CS and prelabour CS (positively), and for (ρ = 0.87; Additional file 1:Table S8). women in midwife-led care at the onset of labour, intra- partum CS and instrumental vaginal birth (positively). Discussion Regional variation was similar for women in midwife-led In this nationwide study, most interregional variation compared to those in obstetrician-led care within the was found for the different types of pain medication same region. PPH occurred more often in regions where (epidural analgesia or other pharmacological pain relief), rates of augmentation of labour were higher. Antepartum Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 10 of 18 1,8 = 0.19 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for prelabour CS with 99% confidence interval Adjusted OR for induction of labour with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country . (rho) is the coefficient between the two point markers in the figure (prelabour CS and induction of labour), which corresponds with the correlation coefficient described in table 7. Fig. 6 Regional variation of prelabour CS and induction of labour for all women and neonatal mortality rates did not vary significantly. However, it is unlikely that this explains all variations ob- Regions with higher intervention rates did not have lower served, because adjustments for maternal characteristics did rates of adverse neonatal and maternal outcomes, or vice not lead to considerable changes in regional variation. Be- versa. sides, it does not explain the large variation in pain medica- tion and involvement of a paediatrician. On the other hand, Limitations and strengths regional variations in subgroups of different ethnic back- This study is based on routinely collected data. Reporting grounds could explain some of the variations. Secondly, re- bias is an issue in any register dataset, particularly for sub- gions with higher rates of referrals from midwife-led to jective outcomes, such as Apgar score and blood loss. Pitfalls obstetrician-led care, may have more low- or medium-risk in the use of these register-based data are described in a re- women in obstetrician-led care, which might be reflected by cent article of De Jonge et al. [44]. Misclassification is ex- lower intervention rates in obstetrician-led care, and higher pected to be similar across regions and it is unlikely that it rates in midwife-led care. However, our results showed accounts for any of the variations. Another limitation is the strong positive correlations between intervention rates in absence or incompleteness of some variables in the dataset, midwife-led and obstetrician-led care within the same re- such as maternal body mass index, congenital disorders, and gion. Last, by calculating correlation coefficients between re- obstetric history of low birth weight or previous CS. gional adjusted ORs, it was not possible to account for the Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 11 of 18 1,8 = 0.60 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB 1,8 = 0.45 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB Fig. 7 a: Regional variation of intrapartum CS and instrumental birth for women in midwife-led care. b: Regional variation of intrapartum CS and instrumental birth for women in obstetrician-led care Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 12 of 18 Table 2 Childbirth intervention rates by region total, and in subgroups by setting, stratified by parity (percentages) Nulliparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Total n All women 276,701 8901 9564 6785 18,051 7233 30,961 23,662 49,582 63,785 4853 38,544 14,780 Midwife 153,091 4827 5701 3550 10,292 3979 18,559 14,293 29,280 32,817 2695 20,2019 6879 Obstetrician 121,612 4045 3831 3217 7648 3230 12,247 9266 19,663 30,283 2140 18,198 7844 Induction of labour, % All women 21.2 24.8 20.7 26.2 23.3 20.8 18.6 18.0 19.1 23.0 22.4 21.4 24.4 Obstetrician 48.2 54.6 52.2 55.1 54.3 46.9 47.0 46.1 47.6 48.0 51.2 45.5 46.3 Augmentation after spontaneous onset of labour, % All women 42.9 40.7 38.0 41.5 36.2 48.4 44.3 45.9 43.7 42.1 33.5 45.6 42.2 Midwife 39.1 37.9 34.8 37.5 32.7 43.3 41.2 43.4 40.3 37.1 29.5 41.8 37.6 Obstetrician 54.5 49.9 51.5 53.9 48.9 62.6 55.1 54.7 55.6 54.9 47.1 56.0 52.0 Intrapartum oxytocin use, % All women 62.2 62.4 61.7 63.3 59.0 66.5 64.3 65.6 63.4 62.4 55.1 59.9 58.0 Obstetrician 61.6 64.6 64.4 67.5 60.9 69.5 63.2 63.7 62.1 60.9 56.5 58.7 58.4 Epidural, % All women without prelabour CS 27.4 25.4 20.1 12.3 27.7 13.7 27.6 31.0 22.3 27.3 19.1 37.5 36.4 Midwife 19.8 19.5 14.2 7.9 19.8 8.7 20.9 24.4 16.0 17.9 13.0 28.8 26.2 Obstetrician without prelabour CS 38.1 33.1 30.0 17.7 39.3 20.1 38.7 42.4 32.6 38.5 27.7 48.4 46.3 Other pharmacological pain relief, % All women without prelabour CS 21.6 20.1 20.6 38.2 16.2 43.0 17.6 14.8 24.6 22.3 25.6 17.2 27.9 Midwife 17.7 14.7 16.5 30.0 13.0 35.4 14.8 13.1 21.2 17.6 19.0 14.8 20.9 Obstetrician without prelabour CS 27.1 27.1 27.6 48.0 20.8 53.1 22.0 17.7 29.8 28.0 34.8 20.1 34.7 Spontaneous vaginal birth, % All women 65.2 62.4 64.0 66.0 64.1 64.6 67.4 66.8 64.6 64.1 66.2 66.2 64.9 Midwife 74.3 72.0 72.7 74.5 73.1 71.8 75.6 75.2 73.2 74.3 75.9 75.7 75.8 Obstetrician 53.6 51.2 51.2 56.6 51.9 55.9 54.9 53.9 51.8 53.0 53.9 55.4 55.4 Instrumental vaginal birth, % All women (without prelabour CS) 17.9 19.3 17.8 17.5 19.4 18.5 17.1 17.2 18.3 19.1 17.0 16.2 16.6 Midwife 17.0 18.5 17.1 17.7 18.3 18.5 16.4 16.3 17.5 17.3 15.6 15.9 15.9 Obstetrician (without prelabour CS) 19.2 20.2 18.9 17.4 21.1 18.5 18.2 18.7 19.7 21.1 18.9 16.5 17.3 Caesarean Section, % All women 17.8 19.3 19.0 17.2 17.4 17.6 16.3 16.7 17.9 17.7 17.6 18.5 19.4 Prelabour CS, % All women 4.5 4.6 4.7 4.1 4.4 3.6 4.1 4.2 4.3 4.4 4.6 5.2 5.8 Obstetrician 10.2 10.0 11.5 8.6 10.2 7.9 10.2 10.6 10.7 9.2 10.4 11.1 10.8 Intrapartum CS, % All women (without prelabour CS) 13.9 15.4 15.1 13.7 13.6 14.6 12.7 13.1 14.2 13.9 13.7 14.0 14.4 Midwife 8.6 9.6 10.2 7.7 8.5 9.7 7.9 8.5 9.3 8.4 8.5 8.3 8.2 Obstetrician (without prelabour CS) 21.2 23.0 23.3 20.9 21.2 21.0 20.7 21.1 22.3 20.5 21.0 21.2 20.6 Involvement paediatrician < 24 h, % All women 50.4 59.6 49.9 51.1 47.7 48.3 55.9 60.0 36.9 50.8 46.9 53.0 60.3 Midwife 38.1 45.6 37.9 37.2 34.8 38.1 43.4 49.0 26.9 36.5 32.5 42.5 47.0 Obstetrician 65.8 76.3 67.6 66.5 64.8 60.8 74.7 76.9 51.6 66.4 65.6 64.5 71.9 Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 13 of 18 Table 2 Childbirth intervention rates by region total, and in subgroups by setting, stratified by parity (percentages) (Continued) Nulliparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Multiparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Total n All women 338,029 10,540 13,004 9090 24,818 10,228 40,325 29,231 56,366 75,788 6474 45,643 16,522 Midwife 174,918 5186 7200 4334 13,630 4963 22,842 16,308 30,470 37,206 3373 21,821 7585 Obstetrician 161,286 5331 5765 4735 11,070 5246 17,324 12,812 25,414 37,940 3082 23,705 8862 Induction of labour, % All women 19.7 23.8 19.0 25.4 20.2 22.2 17.7 16.6 18.0 21.1 20.6 20.1 21.2 Obstetrician 41.1 47.0 43.0 48.8 44.8 43.3 41.1 37.6 39.4 41.7 43.3 38.8 39.7 Augmentation after spontaneous onset of labour, % All women 17.3 14.5 14.8 18.0 14.0 22.6 17.2 16.1 17.9 18.4 12.4 18.8 16.6 Midwife 11.2 8.8 9.5 12.0 8.6 14.2 11.3 11.5 12.1 11.6 7.1 11.7 10.1 Obstetrician 33.2 29.3 32.5 33.2 30.9 41.3 34.3 29.4 34.6 33.9 27.2 33.8 30.2 Intrapartum oxytocin use, % All women 44.7 47.0 47.6 51.7 44.5 51.7 46.3 43.4 45.4 45.6 41.4 40.1 39.7 Obstetrician 45.8 50.3 50.0 54.2 46.6 54.3 47.8 43.9 45.8 45.9 42.9 41.0 41.5 Epidural, % All women without prelabour CS 9.6 8.9 7.0 4.6 8.4 4.9 9.3 10.4 8.0 9.7 7.6 13.8 13.8 Midwife 3.0 2.7 2.0 0.8 2.2 1.6 3.0 4.2 2.6 2.6 2.3 4.8 4.3 Obstetrician without prelabour CS 18.1 16.0 14.5 8.6 17.5 8.6 18.7 19.9 15.8 18.1 14.7 23.8 23.6 Other pharmacological pain relief, % All women without prelabour CS 14.5 12.4 14.3 22.9 11.7 26.8 11.2 9.8 14.5 15.1 14.4 15.0 19.9 Midwife 6.6 5.0 5.6 9.5 5.2 12.6 5.3 5.1 7.2 6.5 4.7 7.9 8.4 Obstetrician without prelabour CS 24.6 20.8 27.3 37.3 21.3 42.5 20.0 17.0 25.0 25.1 26.8 23.0 31.7 Spontaneous vaginal birth, % All women 83.7 82.9 82.5 83.8 83.6 84.9 86.1 84.2 82.8 83.4 83.9 83.6 81.7 Midwife 96.9 96.6 96.2 97.3 96.6 96.9 97.2 97.1 96.8 96.8 97.1 96.9 97.1 Obstetrician 69.3 69.7 65.2 71.5 67.5 73.6 71.5 67.9 66.0 70.1 69.4 71.1 68.6 Instrumental vaginal birth, % All women (without prelabour CS) 3.5 3.7 4.1 3.5 4.2 3.1 3.3 3.1 3.1 3.8 3.7 3.1 3.5 Midwife 1.8 1.7 2.1 1.7 2.2 1.6 1.6 1.7 1.6 1.9 1.8 1.7 1.7 Obstetrician (without prelabour CS) 5.7 6.0 7.0 5.5 7.2 4.8 5.9 5.3 5.4 6.0 6.1 4.6 5.4 Caesarean Section, % All women 13.2 13.7 13.8 13.0 12.6 12.2 10.8 12.9 14.3 13.2 12.7 13.6 15.2 Prelabour CS, % All women 7.8 7.9 7.8 7.7 7.7 7.2 5.8 8.0 8.5 7.9 7.7 8.2 9.8 Obstetrician 16.4 15.6 17.6 14.7 17.1 14.0 13.4 18.2 18.8 15.6 16.3 15.9 18.0 Intrapartum CS, % All women (without prelabour CS) 5.8 6.2 6.4 5.7 5.3 5.4 5.3 5.4 6.3 5.8 5.4 5.9 6.0 Midwife 1.3 1.7 1.6 1.0 1.2 1.5 1.2 1.2 1.5 1.4 1.1 1.4 1.1 Obstetrician (without prelabour CS) 11.6 11.4 13.8 10.7 11.4 9.6 11.5 11.8 13.4 11.0 11.2 10.9 11.0 Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 14 of 18 Table 2 Childbirth intervention rates by region total, and in subgroups by setting, stratified by parity (percentages) (Continued) Nulliparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Involvement paediatrician < 24 h, % All women 35.6 41.1 34.5 36.3 33.9 34.0 37.8 41.9 25.6 37.0 36.0 37.0 42.7 Midwife 14.6 16.6 14.2 13.7 13.1 14.8 16.4 19.6 9.2 14.4 11.7 16.8 19.2 Obstetrician 58.2 65.0 59.9 57.0 59.3 52.0 66.1 70.2 45.2 59.1 62.7 55.5 62.7 Percentage of missing data: 0.6 for midwife- or obstetrician-led care, 0.7% for spontaneous vaginal birth, 0.7% for instrumental birth, 0.7% for caesarean section, 0.8% for induction of labour, 0.6% for augmentation of labour, 0.0% for oxytocin use, 0.4% for epidural and other pharmacological pain relief, 0.3% forinvolvement paediatrician < 24 h confidence intervals of the ORs. Therefore, these calculated PPH. However, the results are consistent with findings correlations are only a rough indicator of relevant and sig- from previous studies that showed an association nificant correlations between variables. Besides, in case of between oxytocin use during labour and severe PPH [52, minor variation in ORs, a Spearman’s rank correlation coef- 53]. Other studies showed greater variations between ficient readily becomes insignificant, since it is based on regions within a country than our study [29, 31–33, 54, ranking of the twelve regions. The Spearman’srankcorrel- 55]. Although variation in for instance augmentation of ation coefficients should be interpreted with caution, also labour appears limited, an additional 10,300 nulliparous because of multiple testing. women would receive oxytocin for augmentation each To our knowledge, this is the first study investigating re- year if the highest regional rate would become the na- gional variations of multiple interventions in childbirth in tional rate, compared to the lowest rate. Even in case of the Netherlands. A major strength of this study is its inclu- limited variation in intervention rates, crude numbers sion of almost all births in the Netherlands between 2010 show that variation might nonetheless be unwarranted. and 2013. As stated in a Lancet series on Midwifery, avail- An aim of evidence-based practice is to minimize un- able data strongly suggest an urgent need for more re- warranted variation in the use of interventions [56, 57]. search to assess the appropriate use of interventions in However, it is still unknown what would be the best rate childbirth [10]. This study contributes to this need. Be- for augmentation of labour and for other interventions. cause the results were described separately for women in Regions with higher rates of augmentation of labour had midwife- and obstetrician-led care at the onset labour, it on one hand higher rates of PPH, but on the other hand has become clearer in which subgroups variations in inter- lower instrumental vaginal birth rates. Whether there is ventions are more prevalent. Another strength of this ex- a causal relationship between these variables, needs to plorative study is the comparison of groups of births based be investigated in further research. Generally, the opti- on the mothers’ residential postal codes rather than her mal rate is the lowest rate with comparable neonatal and place of birth. Presence of a tertiary academic hospital in a maternal outcomes. In our study adverse neonatal and region has had limited impact on results in this way, since maternal outcomes were not lower in regions with in all regions both low- and high risk women are repre- higher intervention rates. However, achieving a low sented, women have access to all types of birth settings, intervention rate should not be an aim in itself [10, 57]. while not all types are present in all regions, and con- It is not possible to identify the optimal rate of interven- founders are more equally distributed than between hospi- tions based on this study. An essential element in improv- tals [44]. However, other confounders, such as distance to ing quality of care, is that care providers critically audit a hospital, may still have influenced the outcomes. remarkably high and low rates [10, 58]. This study intends Multilevel analyses were not performed, since the aim to contribute to this debate. Following national guidelines of this study was to explore regional variations that are and using the recommendations of the WHO might not explained by maternal characteristics but may be help in achieving the optimal use of interventions explained by variations between care professionals and/ [15–17, 23, 58]. or care settings (midwifery practices, hospitals). On the other hand, differences in regional guidelines and in adherence to national guidelines may explain a part Interpretation and further research of the large variation in type of pain medication and in- The results from previous studies on regional variations volvement of a paediatrician. Use of epidural analgesia for in perinatal mortality and PPH in the Netherlands were women with a single fetus in cephalic position after not completely consistent with our results, probably due 37 weeks’ gestation, has almost tripled between 2000 and to older data and different samples [49, 51]. It is not 2009 in the Netherlands (from 7.7 to 21.9%) [59]. In 2008, possible to establish causal relationship in our study, for a multidisciplinary guideline on pain medication was pub- instance between augmentation of labour and severe lished, in which adequate pain relief upon request for all Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 15 of 18 Table 3 Neonatal and maternal outcomes by region (percentages, crude and adjusted ORs, compared to weighted mean, with 99% CIs Total GR FR DR OV FL GD UT NH ZH ZL NB LB 614,661 19,441 22,568 15,875 42,860 17,461 71,284 52,886 105,944 139,567 11,327 84,147 31,301 Antepartum and 717 23 32 17 42 27 97 62 126 159 11 88 33 intrapartum stillbirth, (0.12) (0.12) 2(0.14) (0.11) (0.10) (0.15) (0.14) (0.12) (0.12) (0.11) (0.10) (0.10) (0.11) n (%) Crude OR [99% CI] 1.02 1.22 0.92 0.84 1.33 1.17 1.01 1.02 0.98 0.83 0.90 0.90 [0.61– [0.79– [0.51– [0.57– [0.83– [0.89– [0.73– [0.80– [0.78– [0.41– [0.68– [0.59– 1.69] 1.88] 1.65] 1.24] 2.13] 1.53] 1.39] 1.31] 1.23] 1.71] 1.19] 1.39] aOR [99% CI] 1.04 1.26 0.93 0.90 1.41 1.13 1.07 0.97 0.97 0.75 0.85 0.89 [0.62– [0.81– [0.51– [0.61– [0.86– [0.85– [0.76– [0.74– [0.75– [0.35– [0.63– [0.58– 1.73] 1.97] 1.71] 1.33] 2.32] 1.50] 1.50] 1.27] 1.25] 1.61] 1.14] 1.37] Neonatal mortality 471 14 13 12 29 14 72 42 85 98 12 52 28 up to 7 days, n (%) (0.08) (0.07) (0.06) (0.08) (0.07) (0.08) (0.10) (0.08) (0.08) (0.07) (0.11) (0.06) (0.09) Crude OR [99% CI] 0.93 0.75 0.98 0.88 1.04 1.31 1.03 1.04 0.91 1.37 0.80 1.16 [0.49– [0.38– [0.49– [0.55– [0.54– [0.95– [0.69– [0.77– [0.68– [0.68– [0.56– [0.72– 1.78] 1.46] 1.97] 1.39] 1.99] 1.80] 1.53] 1.40] 1.21] 2.76] 1.15] 1.86] aOR [99% CI] 0.93 0.76 1.06 0.83 1.04 1.34 1.02 1.01 0.92 1.38 0.80 1.08 [0.48– [0.39– [0.52– [0.51– [0.52– [0.97– [0.67– [0.73– [0.67– [0.68– [0.56– [0.67– 1.79] 1.51] 2.14] 1.36] 2.11] 1.86] 1.57] 1.40] 1.27] 2.79] 1.16] 1.76] Apgar score below 6410 291 280 132 354 163 715 460 1136 1735 83 777 284 7 at 5 minutes , n (%) (1.00) (1.5) (1.2) (0.8) (0.8) (0.9) (1.0) (0.9) (1.1) (1.2) (0.7) (0.9) (0.9) Crude OR [99% CI] 1.53 1.26 0.84 0.84 0.95 1.02 0.88 1.09 1.26 0.74 0.94 0.92 [1.32– [1.09– [0.68– [0.73– [0.78– [0.92– [0.78– [1.00– [1.17– [0.57– [0.85– [0.79– 1.77] 1.46] 1.04] 0.96] 1.14] 1.12] 0.99] 1.18] 1.36] 0.96] 1.03] 1.07] aOR [99% CI] 1.47 1.28 0.90 0.85 0.96 1.05 0.88 0.99 1.18 0.78 0.94 0.92 [1.26– [1.10– [0.73– [0.74– [0.78– [0.95– [0.78– [0.90– [1.09– [0.60– [0.85– [0.79– 1.71] 1.49] 1.12] 0.98] 1.18] 1.17] 0.997] 1.08] 1.28] 1.02] 1.03] 1.07] 3rd and 4th degree 14,065 432 528 423 1061 369 1638 1369 2741 2725 173 1919 687 perineal tear for (2.76) (2.68) (2.84) (3.15) (2.95) (2.49) (2.68) (3.07) (3.13) (2.38) (1.83) (2.79) (2.73) vaginal births, % Crude OR [99% CI] 0.99 1.05 1.17 1.10 0.92 0.99 1.14 1.16 0.88 0.67 1.03 1.01 [0.88– [0.94– [1.04– [1.01– [0.81– [0.93– [1.06– [1.10– [0.83– [0.56– [0.97– [0.92– 1.12] 1.17] 1.32] 1.19] 1.04] 1.06] 1.23] 1.23] 0.93] 0.81] 1.10] 1.11] aOR [99% CI] 1.00 1.09 1.17 1.10 0.96 0.99 1.09 1.15 0.88 0.70 1.01 1.01 [0.88– [0.98– [1.03– [1.01– [0.83– [0.92– [1.01– [1.08– [0.82– [0.58– [0.95– [0.92– 1.12] 1.22] 1.33] 1.91] 1.10] 1.06] 1.18] 1.22] 0.93] 0.84] 1.08] 1.11] Postpartum 35,868 1088 1147 977 2283 1041 4610 3054 6155 7832 411 5430 1840 haemorrhages (6.00) (5.62) (5.17) (6.19) (5.41) (5.99) (6.53) (5.85) (6.03) (5.79) (3.72) (6.88) (5.95) ≥1000 ml, % Crude OR [99% CI] 0.99 0.90 1.09 0.95 1.05 1.16 1.03 1.06 1.02 0.64 1.22 1.05 [0.91– [0.84– [1.01– [0.90– [0.97– [1.11– [0.98– [1.02– [0.98– [0.57– [1.17– [0.99– 1.06] 0.97] 1.18] 0.998] 1.14] 1.20] 1.08] 1.10] 1.05] 0.72] 1.27] 1.11] aOR [99% CI] 0.99 0.92 1.11 0.94 1.09 1.14 0.98 1.04 1.02 0.66 1.20 1.04 [0.92– [0.85– [1.02– [0.89– [0.998– [1.09– [0.93– [0.99– [0.99– [0.58– [1.15– [0.98– 1.07] 0.99] 1.21] 0.995] 1.18] 1.19] 1.03] 1.08] 1.06] 0.74] 1.25] 1.10] Odds ratios, adjusted for parity, maternal age, ethnic background, socioeconomic status and urbanisation Antepartum and intrapartum stillbirth cases are excluded for analyses of Apgar score below 7 at 5 min Percentage of missing data: 0.0% for antepartum and intrapartum stillbirth, 0.1% for neonatal mortality, 0.1% for Apgar score below 7 at 5 minutes, 1.4% for 3rd and 4th degree perineal tear, 2.7% for postpartum haemorrhages > 1000 ml women during labour was advised, with epidural analgesia The large variation in rates of pain medication sug- as the most effective method for pain relief. Two random- gests different degrees of implementation of evidence ized controlled trials showed that women were more satis- and national guidelines, leading to disparity in acces- fied with epidural analgesia compared to patient- sibility to pain medication. Furthermore, the absence controlled remifentanil [60, 61], but access to pain medi- of a national guideline on when a paediatrician needs cation should not be at the expense of continuous sup- to be involved after birth and differences in accessi- port, which can reduce the need for pain medication [22]. bility may explain a part of the large variation in the Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 16 of 18 rates of paediatric involvement, leading to differences Additional files in care and costs. Further research is required to Additional file 1: Tables with correlations within and between examine which medical and non-medical factors may interventions and obstetric outcomes tested with Spearman’s rho: Table explain the large variations in pain medication and S5. Correlations within interventions among women in midwife-led and involvement of a paediatrician. interventions among women in obstetrician-led care at the onset of labour; Table S6. Correlations between interventions in subgroups of Clinical practice is influenced by characteristics of the women in midwife- or obstetrician-led care at the onset of labour; Table care provider, such as age, educational background, S7. Correlations between interventions; Table S8. Correlations between perceptions of risks, and views on childbirth [62–66]. interventions and obstetric outcomes (DOCX 22 kb) Culture within the work environment may encourage Additional file 2: A table with multivariable logistic regression of intervention rates by region, in the following subgroups: all women; care providers to take similar decisions, and variations women in midwife-led care at the onset labour; women in obstetrician- are therefore not merely individual [67]. Differences in led care at the onset of labour. Table S4: Crude and adjusted* ORs of perceptions and attitudes may result in differences in childbirth interventions by region, compared to the weighted mean, with 99% CIs (DOCX 59 kb) local practice and guidelines. The fact that variations were found between regions, even after adjustments for Abbreviations maternal characteristics, suggests that there may be CS: Caesarean section; OR: Odds ratio; PPH: Postpartum haemorrhage of cultural differences between regions, reflected in 1000 ml or more; SES: Socioeconomic status; VU: Vrije Universiteit; differences in the views of care providers on childbirth WHO: World Health Organization [63, 68, 69]. The large variation, in particular for pain Acknowledgements medication and involvement of a paediatrician, cannot We thank Perined for the use of the national database and Janneke Wilschut be explained by clinical variations only. Similarities in for giving advice on the statistics. variations in interventions that were found between women in midwife-led and obstetrician-led care, Funding This study was funded by AVAG, Amsterdam Public Health Research Institute, suggest similar practice by midwives and obstetricians VU University Medical Center. There was no external funding for this study. within regions. These similarities existed in interven- tions with minor variation as well as in those with Availability of data and materials The data that support the findings of this study are available from Perined, considerable variation. The results of this study call but restrictions apply to the availability of these data, which were used under for implementation of evidence-based interventions, license for the current study, and so are not publicly available. Data are and for investigation into indications for the use of however available from the authors upon reasonable request and with permission of Perined. interventions in childbirth [10]. The Robson Classifi- cation System could be used to explore subgroups of Authors’ contributions women that account for the greatest variation [70]. AESS and AdJ conceived the study and AESS wrote the paper. AESS, DCZ Limited variation in some of the interventions in our and CG conducted the analyses. AE, DCZ, MN, TvdA, CV, CG, FS and AdJ contributed to the methods of the study and the interpretation of the study may indicate consensus about its use. However, findings, and revised earlier drafts of the article. All authors read and variations may be greater between midwifery prac- approved the final manuscript. tices, hospitals, collaborations or care providers, than Ethics approval and consent to participate between regions where variations between organisa- The VU University Medical Center confirmed that ethical approval was not tions and practitioners will have been averaged. In required for this study, according to the Dutch legislation (reference WC2016– further research, variations within the regions should 055; http://www.ccmo.nl/en/your-research-does-it-fall-under-the-wmo). therefore be investigated. Competing interests The authors declare that they have no competing interests. Conclusions Publisher’sNote The greatest variation was found for the type of pain Springer Nature remains neutral with regard to jurisdictional claims in medication and the involvement of a paediatrician, and published maps and institutional affiliations. the least for instrumental vaginal birth and intrapartum Author details CS rates. The rates of adverse outcomes were not lower Department of Midwifery Science, AVAG, Amsterdam Public Health research in regions with higher intervention rates. Care providers Institute, VU University Medical Center, Van der Boechorststraat 7, 1081 BT should critically audit remarkable variations, since these Amsterdam, the Netherlands. Research Centre for Midwifery Science, Zuyd University, Universiteitssingel 60, 6229 ER Maastricht, the Netherlands. may be unwarranted. Variation may be explained to Department of Obstetrics, Leiden University Medical Center, Albinusdreef 2, some extent by a difference in the degree of implemen- 2333 ZA Leiden, the Netherlands. Department of Obstetrics and tation of national guidelines between regions. Further re- Gynaecology, Maxima Medical Centre, De Run 4600, PO Box 7777, 5500 MB Veldhoven, the Netherlands. NIVEL (Netherlands Institute for Health Services search should therefore focus on variations in evidence- Research), PO Box 1568, 3500 BN Utrecht, the Netherlands. Department of based interventions and indications for the use of inter- General Practice & Elderly Care Medicine, Amsterdam Public Health Research ventions in childbirth. Institute, VU University Medical Center, Amsterdam, the Netherlands. Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 17 of 18 Received: 7 March 2018 Accepted: 30 April 2018 25. Nippita TA, Lee YY, Patterson JA, Ford JB, Morris JM, Nicholl MC, et al. 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Regional variations in childbirth interventions in the Netherlands: a nationwide explorative study

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Medicine & Public Health; Reproductive Medicine; Maternal and Child Health; Gynecology
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Abstract

Background: Although interventions in childbirth are important in order to prevent neonatal and maternal morbidity and mortality, non-indicated use may cause avoidable harm. Regional variations in intervention rates, which cannot be explained by maternal characteristics, may indicate over- and underuse. The aim of this study is to explore regional variations in childbirth interventions in the Netherlands and their associations with interventions and adverse outcomes, controlled for maternal characteristics. Methods: Childbirth intervention rates were compared between twelve Dutch regions, using data from the national perinatal birth register for 2010–2013. All single childbirths from 37 weeks’ gestation onwards were included. Primary outcomes were induction and augmentation of labour, pain medication, instrumental birth, caesarean section (prelabour, intrapartum) and paediatric involvement. Secondary outcomes were adverse neonatal and maternal outcomes. Multivariable logistic regression analyses were used to adjust for maternal characteristics. Associations were expressed in Spearman’s rank correlation coefficients. Results: Most variation was found for type of pain medication and paediatric involvement. Epidural analgesia rates varied from between 12 and 38% (nulliparous) and from between 5 and 14% (multiparous women). These rates were negatively correlated with rates of other pharmacological pain relief, which varied from between 15 and 43% (nulliparous) and from between 10 and 27% (multiparous). Rates of paediatric involvement varied from between 37 and 60% (nulliparous) and from between 26 and 43% (multiparous). For instrumental vaginal births, rates varied from between 16 and 19% (nulliparous) and from between 3 and 4% (multiparous). For intrapartum caesarean section, the variation was 13–15% and 5–6%, respectively. A positive correlation was found between intervention rates in midwife- led and obstetrician-led care at the onset of labour within the same region. Adverse neonatal and maternal outcomes were not lower in regions with higher intervention rates. Higher augmentation of labour rates correlated with higher rates of severe postpartum haemorrhage. Conclusions: Most variation was found for type of pain medication and paediatric involvement, and least for instrumental vaginal births and intrapartum caesarean sections. Care providers and policy makers should critically audit remarkable variations, since these may be unwarranted. Limited variation for some interventions may indicate consensus for their use. Further research should focus on variations in evidence-based interventions and indications for the use of interventions in childbirth. Keywords: Childbirth, Interventions, Obstetric, Regional, Variations, Outcomes, Caesarean section, Induction, Pain relief * Correspondence: a.seijmonsbergen@vumc.nl Department of Midwifery Science, AVAG, Amsterdam Public Health research Institute, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, the Netherlands Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 2 of 18 Background led care in the Netherlands, and controlled for maternal The rates of interventions in childbirth vary worldwide characteristics. [1–4] and have fluctuated over the years [1, 4–7]. Induc- tion of labour and caesarean section (CS) rates have Methods shown a steady increase since the 1970s [1, 4, 6, 8, 9], Data collection which raised concerns [10]. Interventions in childbirth For this nationwide study, we used consolidated data of are important in order to prevent neonatal and maternal the years 2010 to 2013 from Perined, the national peri- morbidity and mortality. However, use without a medical natal register that includes data from almost all births in indication may cause avoidable harm [2, 11–14]. The the Netherlands. Perined aims to improve the quality of World Health Organization (WHO) recommends lim- perinatal care through providing data for research and ited use of interventions during childbirth [15]. Induc- audits on adverse outcomes. The Perined register in- tion and augmentation of labour should only be cludes data from: primary midwife-led care (the national performed on medical indication [16, 17]. However, perinatal database 1); secondary obstetrician-led care there are concerns about poor adherence to this recom- (the national perinatal database 2); paediatric care (the mendation in a significant number of women with un- national neonatal register); and primary midwifery care complicated pregnancies [16–19]. Epidural analgesia is by general practitioners (the national perinatal database the most effective method for pain medication during h). The data are routinely recorded by the care providers labour [20], but is associated with a higher risk of instru- and combined into the Perined register via a validated mental birth, oxytocin use, maternal fever, urinary reten- linkage method [37, 38]. More than 98% of all midwifery tion and complications, such as post-dural puncture practices and obstetric hospital units record their births headache [20, 21]. The decision for pain medication is in this combined database [39]. All single childbirths ultimately based on women’s choice. There is some evi- from 37 weeks’ gestation onwards were included. Exclu- dence that continuous support of labour might reduce sion criteria were missing data on: postal code; parity; or the need for pain medication [22]. Furthermore, the from the national perinatal database 1, covering WHO states that CS rates higher than 10 % at popula- midwife-led care, but where the woman was referred to tion level are not associated with reductions in maternal, obstetrician-led care, covered by the national database 2. neonatal and infant mortality rates [23]. In the Netherlands, low-risk women in primary Variations in intervention rates between high-income midwife-led care are cared for by independent midwives countries may be explained by culture and history, dif- who attend home births, low-risk hospital births, and ferences in population characteristics, maternity care births in alongside and free-standing birth centres. The systems, and national guidelines [12, 15, 24–26]. Clinical Dutch Birth Centre Study showed that health outcomes, guidelines have been used for a long time to harmonise experiences, and costs for low-risk women are similar and rationalise the use of interventions within countries, for planned birth in a birth centre and planned birth in and to improve outcomes [27, 28]. Nevertheless, studies a hospital, both supervised by a primary care midwife comparing regions within countries like England, [40, 41]. When risks for adverse outcomes increase or Ireland, Canada and Germany, have found substantial complications arise, women are referred to obstetrician- variations in rates of induction of labour, epidural anal- led care. Interventions in childbirth such as induction gesia, continuous fetal electronic monitoring, episiot- and augmentation of labour, pain medication, instru- omy, instrumental birth, and CS [29–33]. Additionally, mental birth, and CS, are only available in an Dutch studies have reported variations in rates between obstetrician-led care setting [42, 43]. Intrapartum inter- hospitals, of induction and augmentation of labour, ad- ventions may be used for women in midwife-led care at ministration of sedation and analgesics, episiotomy, in- the onset of labour after referral to obstetrician-led care. strumental birth, and CS [34, 35]. Regional variations in Therefore, intervention rates are not comparable for intervention rates, which cannot be explained by mater- women who are in midwife-led care and women who nal characteristics, may indicate over- and underuse are in obstetrician-led care at the onset of labour. [36]. This is especially true in a relatively small country The VU University Medical Center confirmed that eth- without regional differences in the maternity healthcare ical approval was not required for this study according to system. the Dutch legislation (reference WC2016–055; http://www. The aim of this study was therefore to explore which ccmo.nl/en/your-research-does-it-fall-under-the-wmo). regional variations in intervention rates in childbirth exist, and how these variations are associated both to each other, and to adverse neonatal and maternal out- Interventions comes. These are explored for single childbirths from Births were attributed to one of the twelve Dutch 37 weeks of gestation onwards in midwife- or obstetrician- administrative provinces (further referred to as ‘regions’) Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 3 of 18 according to the residential postal code of the mother. confounders [29, 30, 32, 46–49]: parity (nulliparous, All low-risk women have access to all types of birth set- multiparous); care setting at the onset of labour (mid- tings, but not all types are present in all regions [44]. wife-led, obstetrician-led), maternal age (< 20, 20–24, We adjusted for this by using the residential postal code 25–29, 30–34, 35–39, ≥40 years); ethnic background of the mother. (Dutch, non-Dutch); degree of urbanisation (urban, The following interventions were examined as the pri- intermediate, rural); socioeconomic status (high, mary outcomes: induction of labour; augmentation after a medium, low); gestational age (37 + 0–37 + 6, 38 + 0–40 spontaneous onset of labour; intrapartum oxytocin use; +6, 41 +0–41 + 6, ≥42 weeks); and birth weight (< 2.3rd, epidural analgesia; other pharmacological pain relief; <10th, >90th, > 97.7th percentile). Ethnic background instrumental vaginal birth; CS (prelabour, intrapartum); was reported by the care provider and was defined as and involvement of a paediatrician in the first 24 h after Dutch or non-Dutch, because of inconsistencies in birth. Births from 42 weeks onwards were not excluded, recording non-Dutch subgroups. The degree of urbanisation because they may explain variation in particularly induc- was based on the four digits of the residential postal code of tion of labour rates, and they may reflect different policies the mother. For 2500 or more addresses/km ,the degree of between regions. Artificial rupture of membranes before a urbanisation was categorized as urban, and for less than 500 spontaneous onset of labour was defined as induction of addresses/km as rural. Socioeconomic status [SES] was labour, and administration of oxytocin to stimulate uterine based on a proxy measure indicated by the Netherlands contractions after spontaneously ruptured membranes as Institute for Social Research (SCP), which includes augmentation. A CS after spontaneously ruptured mem- education, employment, and level of income of the branes was defined as intrapartum CS. Intrapartum oxyto- residential postal code area (Statistics Netherlands; https:// cin includes the use of oxytocin for induction or for bronnen.zorggegevens.nl/Bron?naam=Sociaal-Economische- augmentation of labour, but not oxytocin use in the third Status-per-postcodegebied). SES was classified as high, stage of labour. Women with a prelabour CS were medium and low, based on the 25 and 75 percentile excluded from the analyses on pain medication. Women cut-off points. with an intrapartum CS and an epidural, are classified as epidural analgesia for labour pain, since epidural analgesia is generally not used for caesarean sections without prior Data analysis epidural analgesia for labour pain. In Perined ‘other The baseline characteristics were described in percent- pharmacological pain relief’ is specified as: sedatives; non- ages per region. The variation in interventions was opioid analgesics; and opioid analgesics without further analysed overall, and in subgroups according to the care details. The most common opioid analgesics are pethidine setting. Stratification by parity was applied for the crude injections, sometimes combined with a sedative such as rates. Univariable analyses were performed to gain promethazine, and patient-controlled remifentanil [45]. In insight in the variations of intervention rates and child- some births, epidural analgesia and other pharmacological birth outcomes in the twelve regions. All interventions methods for pain medication were both used, and there- and childbirth outcomes mentioned above were included fore, the percentages could not be added up [45]. in the univariable analyses. The percentages of missing data were low, namely from between 0.0 to 2.5% for Neonatal and maternal outcomes baseline characteristics, from between 0.0 to 0.8% for The secondary neonatal and maternal outcomes were: interventions, from between 0.0 to 0.1% for neonatal antepartum and intrapartum stillbirth; neonatal mortal- outcomes, and from between 1.4 to 2.7% for maternal ity; Apgar score below 7 at 5 min; third or fourth degree outcomes. Therefore, cases with missing data were perineal tear among vaginal births; and postpartum excluded. haemorrhage (PPH) of 1000 ml or more. Antepartum Multivariable logistic regression analyses were con- stillbirths with births beyond 37 weeks were included, ducted for all births and stratified by the care setting, since this may influence intervention rates. Neonatal with adjustments for: parity; maternal age; ethnic back- mortality was defined as neonatal death up to 7 days. ground; socioeconomic position; and the degree of Antepartum and intrapartum stillbirths were excluded urbanisation. The results of the multivariable analyses from the analyses on Apgar score. Women who gave were illustrated in figures with maps and boxplots with birth by CS were excluded from the analyses on third or adjusted odds ratios (ORs) and 99% confidence intervals fourth degree perineal tear. (CIs). The weighted overall intervention rate was taken as the reference. This weighted rate was the overall Maternal and neonatal characteristics intervention rate, with the intervention rate of the The following maternal and neonatal characteristics region weighted for the number of women in each were included as independent variables or potential region. A confidence interval of 99% was chosen to Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 4 of 18 limits chance findings due to multiple testing in a large Statistical analyses were performed using SPSS Statis- dataset. Outcome variables were dichotomised and tics 22 (SPSS Inc., Chicago, IL, USA). dummy variables were created to account for potential First, overall results and remarkable associations be- confounders in the multivariable logistic regression ana- tween subgroups of women or between interventions lyses. An important topic of this study, was to explore were described. Second, results for each intervention whether the variation of one intervention was associated were described, starting with those that showed most with the variation of another intervention. Instead of ex- variation. ploring associations with eyeballing only, we quantified these associations by calculating Spearman’srank correl- Results ation coefficients. These were calculated to demonstrate Baseline characteristics the associations of regional adjusted ORs between inter- Figure 1 shows the number of births eligible for inclusion ventions in different care settings, and between interven- in this study and Table 1 describes the maternal and neo- tions and childbirth outcomes. Correlation coefficients natal characteristics. Of the 276,701 births in nulliparous were calculated for the adjusted ORs of the regions, but women, 153,091 were in midwife-led care at the onset of only for outcomes that varied significantly between the re- labour, 121,612 in obstetrician-led care, and for the gions. Since the sample size for all calculated correlations remainder, the care setting was unknown. For births in was the same, namely 12 regions, all correlations with ρ ≥ multiparous women, these numbers were 174,918 and 0.57 or ≤− 0.57 corresponded with a p-value of 0.05. Al- 161,286 respectively. In the regions, the proportion of though the limits for clinically significant correlations are mothers younger than 20 years of age ranged from be- arbitrary, we considered a correlation of ρ ≥ 0.60 tween 0.8 to 2.2%, and of 40 years or older from between or ≤− 0.60 as strong [50], and only these correlations were 2.4 to 4.5%. The lowest proportion of mothers with a non- discussed in the text and indicated in bold in the tables. Dutch ethnicity was 9.3% and the highest 34.6%. In three Women who gave birth in 2010-2013 Women excluded from the study, in order of n = 703,942 exclusion: - multiple gestation (n=23,376) or missing information (n=613) - birthbefore 37 weeks gestation (only singletons: n=47,700) -missing postcode (n=5,888), parity (n=26) or national perinatal database 1 in case of referral to obstetrician-led care (n=11,609) Women who gave birth to a n = 89,212 single child from 37 weeks gestation onwards n = 614,730 Nulliparous women Multiparous women n = 276,701 n = 338,029 In midwife-led In obstetrician- In midwife-led In obstetrician- care at onset led care at Unknown care at onset led care at Unknown of labour onset of labour n = 1,998 of labour onset of labour n= 1,825 n = 153,091 n = 121,612 n = 174,918 n = 161,286 Fig. 1 Study population Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 5 of 18 Table 1 Maternal and neonatal characteristics of women by region GR FR DR OV FL GD UT NH ZH ZL NB LB Total n 19,441 22,568 15,875 42,869 17,461 71,286 52,893 105,948 139,573 11,327 84,187 31,302 Parity, % Nulliparous 45.8 42.4 42.7 42.1 41.4 43.4 44.7 46.8 45.7 42.8 45.8 47.2 Multiparous 54.2 57.6 57.3 57.9 58.6 56.6 55.3 53.2 54.3 57.2 54.2 52.8 Maternal age, % < 20 years 1.9 1.5 1.6 1.2 2.2 1.2 0.8 1.0 1.5 1.6 1.0 1.6 20–24 years 12.4 11.5 11.6 10.0 13.9 10.0 7.5 8.4 11.7 15.2 8.7 10.6 25–29 years 31.2 34.8 35.4 33.4 33.9 31.6 26.7 26.2 30.3 33.9 31.5 32.2 30–34 years 35.4 35.1 34.2 38.0 32.3 37.5 40.6 38.2 35.6 33.1 39.8 37.8 35–39 years 16.1 14.5 14.7 14.9 14.6 16.6 20.9 21.6 17.4 13.6 16.5 15.2 ≥40 years 2.9 2.7 2.5 2.4 3.0 3.1 3.6 4.5 3.5 2.7 2.5 2.7 Ethnic background, % Dutch 85.7 90.7 89.9 86.2 65.4 85.6 77.5 67.1 65.4 87.2 80.1 82.7 Non-Dutch 14.3 9.3 10.1 13.8 34.6 14.4 22.5 32.9 34.6 12.8 19.9 17.3 Urbanisation, % Urban 18.0 4.6 0.0 2.9 0.0 3.8 23.0 39.8 41.7 0.0 9.0 2.5 Intermediate 49.2 47.0 53.6 71.3 72.5 71.4 59.6 49.1 45.0 53.3 70.0 69.7 Rural 32.9 48.5 46.4 25.9 27.5 24.8 17.4 11.1 13.3 46.7 21.0 27.8 Socioeconomic status, % High (p ≥ 75) 9.3 11.8 19.4 16.9 39.2 19.1 35.7 23.5 25.5 7.4 20.0 8.7 Medium (p 25–75) 31.5 34.8 40.5 51.4 36.8 56.0 38.8 39.0 39.1 60.3 55.8 58.4 Low (p ≤ 25) 59.2 53.4 40.0 31.7 24.1 24.9 25.4 37.5 35.4 32.2 24.1 32.9 Gestational age (weeks), % 37 + 0–37 + 6 8.7 8.3 9.2 8.6 8.4 6.7 5.8 6.6 7.6 6.5 7.3 8.8 38 + 0–40 + 6 71.5 71.7 72.5 72.1 73.1 71.6 71.2 72.2 72.8 71.6 72.4 73.9 41 + 0–41 + 6 17.9 18.1 16.9 17.4 16.9 19.3 20.7 19.0 18.3 19.4 18.5 16.5 ≥42 1.8 1.9 1.4 1.8 1.6 2.3 2.3 2.2 1.4 2.5 1.8 0.8 Birth weight, % < 2,3rd percentile 1.7 1.4 1.4 1.5 1.8 1.6 1.7 1.8 1.9 2.0 2.0 2.1 <10th percentile 8.0 6.8 7.3 7.4 9.5 7.8 7.9 8.4 8.9 8.8 9.3 9.7 >90th percentile 11.3 12.9 11.9 11.0 9.8 11.2 10.6 10.3 9.7 10.0 9.0 9.0 > 97,7th percentile 3.0 3.5 3.4 2.9 2.4 3.0 2.7 2.7 2.5 2.4 2.3 2.4 Percentage of missing data: 0.0% for maternal age, 0.4% for ethnic background, 1.1% for urbanisation, 2.5% for socioeconomic status, 0.2% for birth weight regions, there were no urban areas, whereas in all regions Results on the national level there were mothers living in rural areas, with a range of The greatest variation was found for the type of pain medi- between 11.1 and 48.5%. Proportions of mothers with a low cation and whether a paediatrician was involved within socioeconomic status varied from between 24.1 to 59.2%. 24 h after birth, followed by variation in augmentation after Regions with the lowest number of births after a spontaneous onset of labour. Less variation was found for 42 weeks (varying from between 0.8 to 2.5%), had induction of labour and prelabour CSs, and least for instru- higher numbers of births at 37–38 weeks (varying mental vaginal births and intrapartum CSs (Figs. 2, 3, 4, 5, 6 from between 5.8 to 9.2%), and vice versa. We found and 7). Similar variation in intervention rates was found for a similar pattern for birth weight below the 2.3rd, births in midwife-led care compared to those in 10th or above the 90th or 97.7th percentile, with obstetrician-led care at the onset of labour in the same rates varying from between 1.4 to 2.1% for birth region (Additional file 1: Table S5). The adverse neonatal weight below the 2.3rd percentile, and from between and maternal outcomes were not lower in regions with 2.3 to 3.5% for birth weight above the 97.7th. higher intervention rates (Additional file 1:Table S8). Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 6 of 18 2,9 2,8 = 0.61 - 2,7 2,6 2,5 2,4 2,3 2,2 2,1 1,9 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 GR FR DR OV FL GD UT NH ZH ZL NB LB 2,9 2,8 = 0.68 - 2,7 2,6 2,5 2,4 2,3 2,2 2,1 1,9 1,8 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 0,4 0,3 0,2 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for epidural analgesia with 99% confidence interval Adjusted OR for other pharmacological pain relief with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country (rho) is the coefficient between the two point markers in the figure (epidural analgesia and other pharmacological pain relief), which corresponds with the correlation coefficient described in table 6. Fig. 2 a: Regional variation of epidural analgesia and other pharmacological pain relief for women in midwife-led care. b: Regional variation of epidural analgesia and other pharmacological pain relief for women in obstetrician-led care Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 7 of 18 1,7 = 0.67 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 0,4 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for involvement of a paediatrician <24 hrs among women in midwife- led care with 99% confidence interval Adjusted OR for involvement of a paediatrician <24 hrs among women in obstetrician-led care with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country. (rho) is the coefficient between the two point markers in the figure (paediatric involvement for women in midwife-led versus obstetrician-led care), which corresponds with the correlation coefficient described in table 5. Fig. 3 Regional variation of paediatric involvement for women in midwife-led care and obstetrician-led care Regional variations were no significant correlations between the use of pain Table 2 describes the intervention rates by region in sub- medication and augmentation of labour, intrapartum oxy- groups stratified by parity, and Additional file 2: Table S4 tocin use, instrumental vaginal birth, intrapartum CS, or the crude and adjusted ORs with confidence intervals, on spontaneous vaginal birth (Additional file 1: Table S7). As which Figs. 2, 3, 4, 5, 6 and 7 are based. Most variation can be seen from Fig. 3, considerable variation was found was found for the type of pain medication during labour for the involvement of a paediatrician in the first 24 h after (Fig. 2a and b), with epidural analgesia rates varying from birth, with rates varying from between 36.9 to 60.3% for between 12.3 to 37.5% in nulliparous and from between nulliparous and from between 25.6 to 42.7% for multipar- 4.6 to 13.8% in multiparous women, and rates of other ous women (Table 2). pharmacological pain relief varying from between 14.8 to Figure 4 shows maps with variations of spontaneous 43.0% in nulliparous and from between 9.8 to 26.8% in birth rates, CS rates, and rates of intrapartum oxytocin multiparous women without prelabour CS (Table 2). The between regions. Rates of intrapartum oxytocin, used for variation of pain medication was similar for women in induction or augmentation of labour, were found of midwife-led compared to those in obstetrician-led care between 55.1 and 66.5% for nulliparous and of between within the same region, with ρ =0.97 (Additional file 1: 39.7 and 51.7% for multiparous women (Table 2), and Table S5), but rates were lower for women in midwife-led varied significantly across regions (Fig. 4c). Rates of aug- care. Generally, lower rates of other pharmacological pain mentation after a spontaneous onset of labour varied relief were found in regions with higher rates of epidural across regions from between 33.5 to 48.4% for nullipar- analgesia, and vice versa. The correlation coefficient was ous and from between 12.4 to 22.6% for multiparous ρ = − 0.61 for women in midwife-led care and ρ = − 0.68 in women (Table 2). Instrumental vaginal birth rates were obstetrician-led care (Additional file 1: Table S6). There lower (ρ = − 0.61) and spontaneous vaginal birth rates Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 8 of 18 GR=Groningen; FR=Friesland; DR=Drenthe; OV=Overijssel; FL=Flevoland; GD=Gelderland; UT=Utrecht; NH=Noord-Holland; ZH=Zuid-Holland; ZL=Zeeland; NB=Noord-Brabant; LB=Limburg. Fig. 4 Significant differences in adjusted* OR between regions in incidences of: a. spontaneous births. b. caesarean sections. c. intrapartum oxytocin use. (* Adjusted for parity, maternal age, ethnic background, socioeconomic status and urbanisation) were higher (ρ = 0.66; Additional file 1: Table S7) in re- (nulliparous women) and from between 5.3 to 6.4% gions where rates of augmentation of labour were (multiparous women), and instrumental birth rates higher. Variations in augmentation of labour are shown varied from between 16.2 to 19.4% (nulliparous in Fig. 5. women) and from between 3.1 to 4.2% (multiparous Less variation was found for induction of labour, women) (Table 2). For midwife-led care, regions with instrumental vaginal birth, and prelabour and intra- higher intrapartum CS rates had higher instrumental partum CS. Rates of prelabour CS were found of be- birth rates as well (ρ = 0.60), but this correlation was tween 3.6 and 5.8% for all nulliparous and of between not significant in obstetrician-led care at the onset 5.8 and 9.8% for all multiparous women, and induc- labour (ρ =0.45; Additional file 1: Table S6). For all tion of labour rates of between 18.0 and 26.2% for all nulliparous women, a variation of spontaneous vaginal nulliparous and of between 16.6 and 25.4% for all birth rates was found of between 62.4 and 67.4%, and multiparous women (Table 2). Figure 6 illustrates the for multiparous women, of between 81.7 and 86.1% ORs of prelabour CS and induction of labour. Regions (Table 2). with higher rates of prelabour CS had higher rates of intrapartum CS as well (ρ = 0.67), and lower rates of spontaneous vaginal births (ρ = − 0.62; Additional file 1: Neonatal and maternal outcomes Table S7). The results of the multivariable analyses for the child- Compared to the other interventions, least variation birth outcomes are described in Table 3. The overall was found for intrapartum CS and instrumental vaginal incidence of antepartum and intrapartum stillbirth birth for women without prelabour CS (Fig. 7a and b). was 0.12% and of neonatal mortality up to 7 days 0.08%, Intrapartum CS rates varied from between 12.7 to 15.4% but the adjusted ORs did not vary significantly Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 9 of 18 1,8 = 0.76 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for augmentation of labour women in midwife-led care with 99% confidence interval Adjusted OR for augmentation of labour among women in obstetrician-led care with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country. (rho) is the coefficient between the two point markers in the figure (augmentation of labour for women in midwife-led versus obstetrician-led care), which corresponds with the correlation coefficient described in table 5. Fig. 5 Regional variation of augmentation of labour after spontaneous onset for women in midwife-led care and obstetrician-led care between regions (Table 3;not showninfigures). and for the involvement of a paediatrician in the first Correlation coefficients were therefore not calculated 24 h after birth. Less variation was found for prelabour for these outcomes. The incidence of Apgar score CS, augmentation and induction of labour, and least for below 7 at 5 min varied significantly across regions instrumental vaginal birth and intrapartum CS rates. from between 0.7 to 1.5%. For third and fourth Regions with higher rates of one intervention did not degree perineal tear, incidences varied from between have higher rates of all other interventions. Interventions 1.8 to 3.2% and for PPH from between 3.7 to 6.9%. that were correlated, were epidural analgesia and other The only intervention and adverse outcome that pharmacological pain relief (negatively), augmentation of were significantly correlated, were augmentation of labour and instrumental vaginal birth (negatively), intra- labour after a spontaneous onset of labour and PPH partum CS and prelabour CS (positively), and for (ρ = 0.87; Additional file 1:Table S8). women in midwife-led care at the onset of labour, intra- partum CS and instrumental vaginal birth (positively). Discussion Regional variation was similar for women in midwife-led In this nationwide study, most interregional variation compared to those in obstetrician-led care within the was found for the different types of pain medication same region. PPH occurred more often in regions where (epidural analgesia or other pharmacological pain relief), rates of augmentation of labour were higher. Antepartum Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 10 of 18 1,8 = 0.19 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB Adjusted OR for prelabour CS with 99% confidence interval Adjusted OR for induction of labour with 99% confidence interval The reference category (OR of 1.0) is the weighted overall rate of the country . (rho) is the coefficient between the two point markers in the figure (prelabour CS and induction of labour), which corresponds with the correlation coefficient described in table 7. Fig. 6 Regional variation of prelabour CS and induction of labour for all women and neonatal mortality rates did not vary significantly. However, it is unlikely that this explains all variations ob- Regions with higher intervention rates did not have lower served, because adjustments for maternal characteristics did rates of adverse neonatal and maternal outcomes, or vice not lead to considerable changes in regional variation. Be- versa. sides, it does not explain the large variation in pain medica- tion and involvement of a paediatrician. On the other hand, Limitations and strengths regional variations in subgroups of different ethnic back- This study is based on routinely collected data. Reporting grounds could explain some of the variations. Secondly, re- bias is an issue in any register dataset, particularly for sub- gions with higher rates of referrals from midwife-led to jective outcomes, such as Apgar score and blood loss. Pitfalls obstetrician-led care, may have more low- or medium-risk in the use of these register-based data are described in a re- women in obstetrician-led care, which might be reflected by cent article of De Jonge et al. [44]. Misclassification is ex- lower intervention rates in obstetrician-led care, and higher pected to be similar across regions and it is unlikely that it rates in midwife-led care. However, our results showed accounts for any of the variations. Another limitation is the strong positive correlations between intervention rates in absence or incompleteness of some variables in the dataset, midwife-led and obstetrician-led care within the same re- such as maternal body mass index, congenital disorders, and gion. Last, by calculating correlation coefficients between re- obstetric history of low birth weight or previous CS. gional adjusted ORs, it was not possible to account for the Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 11 of 18 1,8 = 0.60 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB 1,8 = 0.45 1,7 1,6 1,5 1,4 1,3 1,2 1,1 0,9 0,8 0,7 0,6 0,5 GR FR DR OV FL GD UT NH ZH ZL NB LB Fig. 7 a: Regional variation of intrapartum CS and instrumental birth for women in midwife-led care. b: Regional variation of intrapartum CS and instrumental birth for women in obstetrician-led care Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 12 of 18 Table 2 Childbirth intervention rates by region total, and in subgroups by setting, stratified by parity (percentages) Nulliparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Total n All women 276,701 8901 9564 6785 18,051 7233 30,961 23,662 49,582 63,785 4853 38,544 14,780 Midwife 153,091 4827 5701 3550 10,292 3979 18,559 14,293 29,280 32,817 2695 20,2019 6879 Obstetrician 121,612 4045 3831 3217 7648 3230 12,247 9266 19,663 30,283 2140 18,198 7844 Induction of labour, % All women 21.2 24.8 20.7 26.2 23.3 20.8 18.6 18.0 19.1 23.0 22.4 21.4 24.4 Obstetrician 48.2 54.6 52.2 55.1 54.3 46.9 47.0 46.1 47.6 48.0 51.2 45.5 46.3 Augmentation after spontaneous onset of labour, % All women 42.9 40.7 38.0 41.5 36.2 48.4 44.3 45.9 43.7 42.1 33.5 45.6 42.2 Midwife 39.1 37.9 34.8 37.5 32.7 43.3 41.2 43.4 40.3 37.1 29.5 41.8 37.6 Obstetrician 54.5 49.9 51.5 53.9 48.9 62.6 55.1 54.7 55.6 54.9 47.1 56.0 52.0 Intrapartum oxytocin use, % All women 62.2 62.4 61.7 63.3 59.0 66.5 64.3 65.6 63.4 62.4 55.1 59.9 58.0 Obstetrician 61.6 64.6 64.4 67.5 60.9 69.5 63.2 63.7 62.1 60.9 56.5 58.7 58.4 Epidural, % All women without prelabour CS 27.4 25.4 20.1 12.3 27.7 13.7 27.6 31.0 22.3 27.3 19.1 37.5 36.4 Midwife 19.8 19.5 14.2 7.9 19.8 8.7 20.9 24.4 16.0 17.9 13.0 28.8 26.2 Obstetrician without prelabour CS 38.1 33.1 30.0 17.7 39.3 20.1 38.7 42.4 32.6 38.5 27.7 48.4 46.3 Other pharmacological pain relief, % All women without prelabour CS 21.6 20.1 20.6 38.2 16.2 43.0 17.6 14.8 24.6 22.3 25.6 17.2 27.9 Midwife 17.7 14.7 16.5 30.0 13.0 35.4 14.8 13.1 21.2 17.6 19.0 14.8 20.9 Obstetrician without prelabour CS 27.1 27.1 27.6 48.0 20.8 53.1 22.0 17.7 29.8 28.0 34.8 20.1 34.7 Spontaneous vaginal birth, % All women 65.2 62.4 64.0 66.0 64.1 64.6 67.4 66.8 64.6 64.1 66.2 66.2 64.9 Midwife 74.3 72.0 72.7 74.5 73.1 71.8 75.6 75.2 73.2 74.3 75.9 75.7 75.8 Obstetrician 53.6 51.2 51.2 56.6 51.9 55.9 54.9 53.9 51.8 53.0 53.9 55.4 55.4 Instrumental vaginal birth, % All women (without prelabour CS) 17.9 19.3 17.8 17.5 19.4 18.5 17.1 17.2 18.3 19.1 17.0 16.2 16.6 Midwife 17.0 18.5 17.1 17.7 18.3 18.5 16.4 16.3 17.5 17.3 15.6 15.9 15.9 Obstetrician (without prelabour CS) 19.2 20.2 18.9 17.4 21.1 18.5 18.2 18.7 19.7 21.1 18.9 16.5 17.3 Caesarean Section, % All women 17.8 19.3 19.0 17.2 17.4 17.6 16.3 16.7 17.9 17.7 17.6 18.5 19.4 Prelabour CS, % All women 4.5 4.6 4.7 4.1 4.4 3.6 4.1 4.2 4.3 4.4 4.6 5.2 5.8 Obstetrician 10.2 10.0 11.5 8.6 10.2 7.9 10.2 10.6 10.7 9.2 10.4 11.1 10.8 Intrapartum CS, % All women (without prelabour CS) 13.9 15.4 15.1 13.7 13.6 14.6 12.7 13.1 14.2 13.9 13.7 14.0 14.4 Midwife 8.6 9.6 10.2 7.7 8.5 9.7 7.9 8.5 9.3 8.4 8.5 8.3 8.2 Obstetrician (without prelabour CS) 21.2 23.0 23.3 20.9 21.2 21.0 20.7 21.1 22.3 20.5 21.0 21.2 20.6 Involvement paediatrician < 24 h, % All women 50.4 59.6 49.9 51.1 47.7 48.3 55.9 60.0 36.9 50.8 46.9 53.0 60.3 Midwife 38.1 45.6 37.9 37.2 34.8 38.1 43.4 49.0 26.9 36.5 32.5 42.5 47.0 Obstetrician 65.8 76.3 67.6 66.5 64.8 60.8 74.7 76.9 51.6 66.4 65.6 64.5 71.9 Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 13 of 18 Table 2 Childbirth intervention rates by region total, and in subgroups by setting, stratified by parity (percentages) (Continued) Nulliparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Multiparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Total n All women 338,029 10,540 13,004 9090 24,818 10,228 40,325 29,231 56,366 75,788 6474 45,643 16,522 Midwife 174,918 5186 7200 4334 13,630 4963 22,842 16,308 30,470 37,206 3373 21,821 7585 Obstetrician 161,286 5331 5765 4735 11,070 5246 17,324 12,812 25,414 37,940 3082 23,705 8862 Induction of labour, % All women 19.7 23.8 19.0 25.4 20.2 22.2 17.7 16.6 18.0 21.1 20.6 20.1 21.2 Obstetrician 41.1 47.0 43.0 48.8 44.8 43.3 41.1 37.6 39.4 41.7 43.3 38.8 39.7 Augmentation after spontaneous onset of labour, % All women 17.3 14.5 14.8 18.0 14.0 22.6 17.2 16.1 17.9 18.4 12.4 18.8 16.6 Midwife 11.2 8.8 9.5 12.0 8.6 14.2 11.3 11.5 12.1 11.6 7.1 11.7 10.1 Obstetrician 33.2 29.3 32.5 33.2 30.9 41.3 34.3 29.4 34.6 33.9 27.2 33.8 30.2 Intrapartum oxytocin use, % All women 44.7 47.0 47.6 51.7 44.5 51.7 46.3 43.4 45.4 45.6 41.4 40.1 39.7 Obstetrician 45.8 50.3 50.0 54.2 46.6 54.3 47.8 43.9 45.8 45.9 42.9 41.0 41.5 Epidural, % All women without prelabour CS 9.6 8.9 7.0 4.6 8.4 4.9 9.3 10.4 8.0 9.7 7.6 13.8 13.8 Midwife 3.0 2.7 2.0 0.8 2.2 1.6 3.0 4.2 2.6 2.6 2.3 4.8 4.3 Obstetrician without prelabour CS 18.1 16.0 14.5 8.6 17.5 8.6 18.7 19.9 15.8 18.1 14.7 23.8 23.6 Other pharmacological pain relief, % All women without prelabour CS 14.5 12.4 14.3 22.9 11.7 26.8 11.2 9.8 14.5 15.1 14.4 15.0 19.9 Midwife 6.6 5.0 5.6 9.5 5.2 12.6 5.3 5.1 7.2 6.5 4.7 7.9 8.4 Obstetrician without prelabour CS 24.6 20.8 27.3 37.3 21.3 42.5 20.0 17.0 25.0 25.1 26.8 23.0 31.7 Spontaneous vaginal birth, % All women 83.7 82.9 82.5 83.8 83.6 84.9 86.1 84.2 82.8 83.4 83.9 83.6 81.7 Midwife 96.9 96.6 96.2 97.3 96.6 96.9 97.2 97.1 96.8 96.8 97.1 96.9 97.1 Obstetrician 69.3 69.7 65.2 71.5 67.5 73.6 71.5 67.9 66.0 70.1 69.4 71.1 68.6 Instrumental vaginal birth, % All women (without prelabour CS) 3.5 3.7 4.1 3.5 4.2 3.1 3.3 3.1 3.1 3.8 3.7 3.1 3.5 Midwife 1.8 1.7 2.1 1.7 2.2 1.6 1.6 1.7 1.6 1.9 1.8 1.7 1.7 Obstetrician (without prelabour CS) 5.7 6.0 7.0 5.5 7.2 4.8 5.9 5.3 5.4 6.0 6.1 4.6 5.4 Caesarean Section, % All women 13.2 13.7 13.8 13.0 12.6 12.2 10.8 12.9 14.3 13.2 12.7 13.6 15.2 Prelabour CS, % All women 7.8 7.9 7.8 7.7 7.7 7.2 5.8 8.0 8.5 7.9 7.7 8.2 9.8 Obstetrician 16.4 15.6 17.6 14.7 17.1 14.0 13.4 18.2 18.8 15.6 16.3 15.9 18.0 Intrapartum CS, % All women (without prelabour CS) 5.8 6.2 6.4 5.7 5.3 5.4 5.3 5.4 6.3 5.8 5.4 5.9 6.0 Midwife 1.3 1.7 1.6 1.0 1.2 1.5 1.2 1.2 1.5 1.4 1.1 1.4 1.1 Obstetrician (without prelabour CS) 11.6 11.4 13.8 10.7 11.4 9.6 11.5 11.8 13.4 11.0 11.2 10.9 11.0 Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 14 of 18 Table 2 Childbirth intervention rates by region total, and in subgroups by setting, stratified by parity (percentages) (Continued) Nulliparous women, total and by care setting at the onset of labour (abbreviated as ‘midwife’ or ‘obstetrician’) Total GR FR DR OV FL GD UT NH ZH ZL NB LB Involvement paediatrician < 24 h, % All women 35.6 41.1 34.5 36.3 33.9 34.0 37.8 41.9 25.6 37.0 36.0 37.0 42.7 Midwife 14.6 16.6 14.2 13.7 13.1 14.8 16.4 19.6 9.2 14.4 11.7 16.8 19.2 Obstetrician 58.2 65.0 59.9 57.0 59.3 52.0 66.1 70.2 45.2 59.1 62.7 55.5 62.7 Percentage of missing data: 0.6 for midwife- or obstetrician-led care, 0.7% for spontaneous vaginal birth, 0.7% for instrumental birth, 0.7% for caesarean section, 0.8% for induction of labour, 0.6% for augmentation of labour, 0.0% for oxytocin use, 0.4% for epidural and other pharmacological pain relief, 0.3% forinvolvement paediatrician < 24 h confidence intervals of the ORs. Therefore, these calculated PPH. However, the results are consistent with findings correlations are only a rough indicator of relevant and sig- from previous studies that showed an association nificant correlations between variables. Besides, in case of between oxytocin use during labour and severe PPH [52, minor variation in ORs, a Spearman’s rank correlation coef- 53]. Other studies showed greater variations between ficient readily becomes insignificant, since it is based on regions within a country than our study [29, 31–33, 54, ranking of the twelve regions. The Spearman’srankcorrel- 55]. Although variation in for instance augmentation of ation coefficients should be interpreted with caution, also labour appears limited, an additional 10,300 nulliparous because of multiple testing. women would receive oxytocin for augmentation each To our knowledge, this is the first study investigating re- year if the highest regional rate would become the na- gional variations of multiple interventions in childbirth in tional rate, compared to the lowest rate. Even in case of the Netherlands. A major strength of this study is its inclu- limited variation in intervention rates, crude numbers sion of almost all births in the Netherlands between 2010 show that variation might nonetheless be unwarranted. and 2013. As stated in a Lancet series on Midwifery, avail- An aim of evidence-based practice is to minimize un- able data strongly suggest an urgent need for more re- warranted variation in the use of interventions [56, 57]. search to assess the appropriate use of interventions in However, it is still unknown what would be the best rate childbirth [10]. This study contributes to this need. Be- for augmentation of labour and for other interventions. cause the results were described separately for women in Regions with higher rates of augmentation of labour had midwife- and obstetrician-led care at the onset labour, it on one hand higher rates of PPH, but on the other hand has become clearer in which subgroups variations in inter- lower instrumental vaginal birth rates. Whether there is ventions are more prevalent. Another strength of this ex- a causal relationship between these variables, needs to plorative study is the comparison of groups of births based be investigated in further research. Generally, the opti- on the mothers’ residential postal codes rather than her mal rate is the lowest rate with comparable neonatal and place of birth. Presence of a tertiary academic hospital in a maternal outcomes. In our study adverse neonatal and region has had limited impact on results in this way, since maternal outcomes were not lower in regions with in all regions both low- and high risk women are repre- higher intervention rates. However, achieving a low sented, women have access to all types of birth settings, intervention rate should not be an aim in itself [10, 57]. while not all types are present in all regions, and con- It is not possible to identify the optimal rate of interven- founders are more equally distributed than between hospi- tions based on this study. An essential element in improv- tals [44]. However, other confounders, such as distance to ing quality of care, is that care providers critically audit a hospital, may still have influenced the outcomes. remarkably high and low rates [10, 58]. This study intends Multilevel analyses were not performed, since the aim to contribute to this debate. Following national guidelines of this study was to explore regional variations that are and using the recommendations of the WHO might not explained by maternal characteristics but may be help in achieving the optimal use of interventions explained by variations between care professionals and/ [15–17, 23, 58]. or care settings (midwifery practices, hospitals). On the other hand, differences in regional guidelines and in adherence to national guidelines may explain a part Interpretation and further research of the large variation in type of pain medication and in- The results from previous studies on regional variations volvement of a paediatrician. Use of epidural analgesia for in perinatal mortality and PPH in the Netherlands were women with a single fetus in cephalic position after not completely consistent with our results, probably due 37 weeks’ gestation, has almost tripled between 2000 and to older data and different samples [49, 51]. It is not 2009 in the Netherlands (from 7.7 to 21.9%) [59]. In 2008, possible to establish causal relationship in our study, for a multidisciplinary guideline on pain medication was pub- instance between augmentation of labour and severe lished, in which adequate pain relief upon request for all Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 15 of 18 Table 3 Neonatal and maternal outcomes by region (percentages, crude and adjusted ORs, compared to weighted mean, with 99% CIs Total GR FR DR OV FL GD UT NH ZH ZL NB LB 614,661 19,441 22,568 15,875 42,860 17,461 71,284 52,886 105,944 139,567 11,327 84,147 31,301 Antepartum and 717 23 32 17 42 27 97 62 126 159 11 88 33 intrapartum stillbirth, (0.12) (0.12) 2(0.14) (0.11) (0.10) (0.15) (0.14) (0.12) (0.12) (0.11) (0.10) (0.10) (0.11) n (%) Crude OR [99% CI] 1.02 1.22 0.92 0.84 1.33 1.17 1.01 1.02 0.98 0.83 0.90 0.90 [0.61– [0.79– [0.51– [0.57– [0.83– [0.89– [0.73– [0.80– [0.78– [0.41– [0.68– [0.59– 1.69] 1.88] 1.65] 1.24] 2.13] 1.53] 1.39] 1.31] 1.23] 1.71] 1.19] 1.39] aOR [99% CI] 1.04 1.26 0.93 0.90 1.41 1.13 1.07 0.97 0.97 0.75 0.85 0.89 [0.62– [0.81– [0.51– [0.61– [0.86– [0.85– [0.76– [0.74– [0.75– [0.35– [0.63– [0.58– 1.73] 1.97] 1.71] 1.33] 2.32] 1.50] 1.50] 1.27] 1.25] 1.61] 1.14] 1.37] Neonatal mortality 471 14 13 12 29 14 72 42 85 98 12 52 28 up to 7 days, n (%) (0.08) (0.07) (0.06) (0.08) (0.07) (0.08) (0.10) (0.08) (0.08) (0.07) (0.11) (0.06) (0.09) Crude OR [99% CI] 0.93 0.75 0.98 0.88 1.04 1.31 1.03 1.04 0.91 1.37 0.80 1.16 [0.49– [0.38– [0.49– [0.55– [0.54– [0.95– [0.69– [0.77– [0.68– [0.68– [0.56– [0.72– 1.78] 1.46] 1.97] 1.39] 1.99] 1.80] 1.53] 1.40] 1.21] 2.76] 1.15] 1.86] aOR [99% CI] 0.93 0.76 1.06 0.83 1.04 1.34 1.02 1.01 0.92 1.38 0.80 1.08 [0.48– [0.39– [0.52– [0.51– [0.52– [0.97– [0.67– [0.73– [0.67– [0.68– [0.56– [0.67– 1.79] 1.51] 2.14] 1.36] 2.11] 1.86] 1.57] 1.40] 1.27] 2.79] 1.16] 1.76] Apgar score below 6410 291 280 132 354 163 715 460 1136 1735 83 777 284 7 at 5 minutes , n (%) (1.00) (1.5) (1.2) (0.8) (0.8) (0.9) (1.0) (0.9) (1.1) (1.2) (0.7) (0.9) (0.9) Crude OR [99% CI] 1.53 1.26 0.84 0.84 0.95 1.02 0.88 1.09 1.26 0.74 0.94 0.92 [1.32– [1.09– [0.68– [0.73– [0.78– [0.92– [0.78– [1.00– [1.17– [0.57– [0.85– [0.79– 1.77] 1.46] 1.04] 0.96] 1.14] 1.12] 0.99] 1.18] 1.36] 0.96] 1.03] 1.07] aOR [99% CI] 1.47 1.28 0.90 0.85 0.96 1.05 0.88 0.99 1.18 0.78 0.94 0.92 [1.26– [1.10– [0.73– [0.74– [0.78– [0.95– [0.78– [0.90– [1.09– [0.60– [0.85– [0.79– 1.71] 1.49] 1.12] 0.98] 1.18] 1.17] 0.997] 1.08] 1.28] 1.02] 1.03] 1.07] 3rd and 4th degree 14,065 432 528 423 1061 369 1638 1369 2741 2725 173 1919 687 perineal tear for (2.76) (2.68) (2.84) (3.15) (2.95) (2.49) (2.68) (3.07) (3.13) (2.38) (1.83) (2.79) (2.73) vaginal births, % Crude OR [99% CI] 0.99 1.05 1.17 1.10 0.92 0.99 1.14 1.16 0.88 0.67 1.03 1.01 [0.88– [0.94– [1.04– [1.01– [0.81– [0.93– [1.06– [1.10– [0.83– [0.56– [0.97– [0.92– 1.12] 1.17] 1.32] 1.19] 1.04] 1.06] 1.23] 1.23] 0.93] 0.81] 1.10] 1.11] aOR [99% CI] 1.00 1.09 1.17 1.10 0.96 0.99 1.09 1.15 0.88 0.70 1.01 1.01 [0.88– [0.98– [1.03– [1.01– [0.83– [0.92– [1.01– [1.08– [0.82– [0.58– [0.95– [0.92– 1.12] 1.22] 1.33] 1.91] 1.10] 1.06] 1.18] 1.22] 0.93] 0.84] 1.08] 1.11] Postpartum 35,868 1088 1147 977 2283 1041 4610 3054 6155 7832 411 5430 1840 haemorrhages (6.00) (5.62) (5.17) (6.19) (5.41) (5.99) (6.53) (5.85) (6.03) (5.79) (3.72) (6.88) (5.95) ≥1000 ml, % Crude OR [99% CI] 0.99 0.90 1.09 0.95 1.05 1.16 1.03 1.06 1.02 0.64 1.22 1.05 [0.91– [0.84– [1.01– [0.90– [0.97– [1.11– [0.98– [1.02– [0.98– [0.57– [1.17– [0.99– 1.06] 0.97] 1.18] 0.998] 1.14] 1.20] 1.08] 1.10] 1.05] 0.72] 1.27] 1.11] aOR [99% CI] 0.99 0.92 1.11 0.94 1.09 1.14 0.98 1.04 1.02 0.66 1.20 1.04 [0.92– [0.85– [1.02– [0.89– [0.998– [1.09– [0.93– [0.99– [0.99– [0.58– [1.15– [0.98– 1.07] 0.99] 1.21] 0.995] 1.18] 1.19] 1.03] 1.08] 1.06] 0.74] 1.25] 1.10] Odds ratios, adjusted for parity, maternal age, ethnic background, socioeconomic status and urbanisation Antepartum and intrapartum stillbirth cases are excluded for analyses of Apgar score below 7 at 5 min Percentage of missing data: 0.0% for antepartum and intrapartum stillbirth, 0.1% for neonatal mortality, 0.1% for Apgar score below 7 at 5 minutes, 1.4% for 3rd and 4th degree perineal tear, 2.7% for postpartum haemorrhages > 1000 ml women during labour was advised, with epidural analgesia The large variation in rates of pain medication sug- as the most effective method for pain relief. Two random- gests different degrees of implementation of evidence ized controlled trials showed that women were more satis- and national guidelines, leading to disparity in acces- fied with epidural analgesia compared to patient- sibility to pain medication. Furthermore, the absence controlled remifentanil [60, 61], but access to pain medi- of a national guideline on when a paediatrician needs cation should not be at the expense of continuous sup- to be involved after birth and differences in accessi- port, which can reduce the need for pain medication [22]. bility may explain a part of the large variation in the Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 16 of 18 rates of paediatric involvement, leading to differences Additional files in care and costs. Further research is required to Additional file 1: Tables with correlations within and between examine which medical and non-medical factors may interventions and obstetric outcomes tested with Spearman’s rho: Table explain the large variations in pain medication and S5. Correlations within interventions among women in midwife-led and involvement of a paediatrician. interventions among women in obstetrician-led care at the onset of labour; Table S6. Correlations between interventions in subgroups of Clinical practice is influenced by characteristics of the women in midwife- or obstetrician-led care at the onset of labour; Table care provider, such as age, educational background, S7. Correlations between interventions; Table S8. Correlations between perceptions of risks, and views on childbirth [62–66]. interventions and obstetric outcomes (DOCX 22 kb) Culture within the work environment may encourage Additional file 2: A table with multivariable logistic regression of intervention rates by region, in the following subgroups: all women; care providers to take similar decisions, and variations women in midwife-led care at the onset labour; women in obstetrician- are therefore not merely individual [67]. Differences in led care at the onset of labour. Table S4: Crude and adjusted* ORs of perceptions and attitudes may result in differences in childbirth interventions by region, compared to the weighted mean, with 99% CIs (DOCX 59 kb) local practice and guidelines. The fact that variations were found between regions, even after adjustments for Abbreviations maternal characteristics, suggests that there may be CS: Caesarean section; OR: Odds ratio; PPH: Postpartum haemorrhage of cultural differences between regions, reflected in 1000 ml or more; SES: Socioeconomic status; VU: Vrije Universiteit; differences in the views of care providers on childbirth WHO: World Health Organization [63, 68, 69]. The large variation, in particular for pain Acknowledgements medication and involvement of a paediatrician, cannot We thank Perined for the use of the national database and Janneke Wilschut be explained by clinical variations only. Similarities in for giving advice on the statistics. variations in interventions that were found between women in midwife-led and obstetrician-led care, Funding This study was funded by AVAG, Amsterdam Public Health Research Institute, suggest similar practice by midwives and obstetricians VU University Medical Center. There was no external funding for this study. within regions. These similarities existed in interven- tions with minor variation as well as in those with Availability of data and materials The data that support the findings of this study are available from Perined, considerable variation. The results of this study call but restrictions apply to the availability of these data, which were used under for implementation of evidence-based interventions, license for the current study, and so are not publicly available. Data are and for investigation into indications for the use of however available from the authors upon reasonable request and with permission of Perined. interventions in childbirth [10]. The Robson Classifi- cation System could be used to explore subgroups of Authors’ contributions women that account for the greatest variation [70]. AESS and AdJ conceived the study and AESS wrote the paper. AESS, DCZ Limited variation in some of the interventions in our and CG conducted the analyses. AE, DCZ, MN, TvdA, CV, CG, FS and AdJ contributed to the methods of the study and the interpretation of the study may indicate consensus about its use. However, findings, and revised earlier drafts of the article. All authors read and variations may be greater between midwifery prac- approved the final manuscript. tices, hospitals, collaborations or care providers, than Ethics approval and consent to participate between regions where variations between organisa- The VU University Medical Center confirmed that ethical approval was not tions and practitioners will have been averaged. In required for this study, according to the Dutch legislation (reference WC2016– further research, variations within the regions should 055; http://www.ccmo.nl/en/your-research-does-it-fall-under-the-wmo). therefore be investigated. Competing interests The authors declare that they have no competing interests. Conclusions Publisher’sNote The greatest variation was found for the type of pain Springer Nature remains neutral with regard to jurisdictional claims in medication and the involvement of a paediatrician, and published maps and institutional affiliations. the least for instrumental vaginal birth and intrapartum Author details CS rates. The rates of adverse outcomes were not lower Department of Midwifery Science, AVAG, Amsterdam Public Health research in regions with higher intervention rates. Care providers Institute, VU University Medical Center, Van der Boechorststraat 7, 1081 BT should critically audit remarkable variations, since these Amsterdam, the Netherlands. Research Centre for Midwifery Science, Zuyd University, Universiteitssingel 60, 6229 ER Maastricht, the Netherlands. may be unwarranted. Variation may be explained to Department of Obstetrics, Leiden University Medical Center, Albinusdreef 2, some extent by a difference in the degree of implemen- 2333 ZA Leiden, the Netherlands. Department of Obstetrics and tation of national guidelines between regions. Further re- Gynaecology, Maxima Medical Centre, De Run 4600, PO Box 7777, 5500 MB Veldhoven, the Netherlands. NIVEL (Netherlands Institute for Health Services search should therefore focus on variations in evidence- Research), PO Box 1568, 3500 BN Utrecht, the Netherlands. Department of based interventions and indications for the use of inter- General Practice & Elderly Care Medicine, Amsterdam Public Health Research ventions in childbirth. Institute, VU University Medical Center, Amsterdam, the Netherlands. Seijmonsbergen-Schermers et al. BMC Pregnancy and Childbirth (2018) 18:192 Page 17 of 18 Received: 7 March 2018 Accepted: 30 April 2018 25. Nippita TA, Lee YY, Patterson JA, Ford JB, Morris JM, Nicholl MC, et al. 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BMC Pregnancy and ChildbirthSpringer Journals

Published: Jun 1, 2018

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