American Journal of Epidemiology

Matthews, Charles E.; Jurj, Adriana L.; Shu, Xiao-ou; Li, Hong-Lan; Yang, Gong; Li, Qi; Gao, Yu-Tang; Zheng, Wei

doi: 10.1093/aje/kwm088pmid: 17478434

This investigation described the effects of exercise, walking, and cycling for transportation, as well as the effect of overall nonexercise physical activity, on mortality in the Shanghai Women's Health Study (19972004). Women without heart disease, stroke, or cancer were followed for an average of 5.7 years (n 67,143), and there were 1,091 deaths from all causes, 537 deaths from cancer, and 251 deaths from cardiovascular diseases. Information about physical activity and relevant covariates was obtained by interview. Proportional hazards models were used to estimate adjusted hazard ratios and 95% confidence intervals. Exercise and cycling for transportation were both inversely and independently associated with all-cause mortality (ptrend < 0.05), but walking for transportation was less strongly associated with reduced risk (ptrend 0.07). Women reporting no regular exercise but who reported 10 or more metabolic equivalent (MET)-hours/day of nonexercise activity were at 2550% reduced risk (ptrend < 0.01) relative to less active women (09.9 MET-hours/day). Among women reporting the least nonexercise activity (09.9 MET-hours/day) but reporting regular exercise participation, exercise was associated with reduced mortality (hazard ratio 0.78, 95% confidence interval: 0.62, 0.99). These findings add new evidence that overall physical activity levels are an important determinant of longevity, and that health benefit can be obtained through an active lifestyle, exercise, or combinations of both.

Sesso, Howard D.

doi: 10.1093/aje/kwm093pmid: 17470453

Numerous epidemiologic studies report an inverse association between increasing levels of regular physical activity and reductions in major morbidity and mortality. Clinical guidelines emphasize the importance of specific amounts of regular physical activity, yet the majority of US adults do not meet these recommended levels. There are comparatively less data on nonexercise, or lifestyle, physical activity that may occur throughout the day in an unstructured setting with variable duration and frequency. In this issue (Am J Epidemiol 2007;165:13431350), both regular exercise and other forms of nonexercise physical activity are examined in relation to total and cause-specific mortality in Chinese women. This work illustrates several important issues in physical activity epidemiology regarding the identification, measurement, and analysis of nonexercise components of physical activity. Unlike semiquantitative food frequency questionnaires for studies of individual foods and nutrients, physical activity epidemiology lacks a prevailing measurement tool and analytical technique by which to examine nonexercise physical activity. Our challenge is therefore to more accurately and consistently measure these more subtle components of nonexercise physical activity to better understand its potential clinical effects and role in disease prevention.

Matthews, Charles E.; Jurj, Adriana L.; Shu, Xiao-ou; Gao, Yu-Tang; Zheng, Wei

doi: 10.1093/aje/kwm087pmid: N/A

Slingerland, Annabelle S.; van Lenthe, Frank J.; Jukema, J. Wouter; Kamphuis, Carlijn B. M.; Looman, Caspar; Giskes, Katrina; Huisman, Martijn; Narayan, K. M. Venkat; Mackenbach, Johan P.; Brug, Johannes

doi: 10.1093/aje/kwm053

Letenneur, L; Proust-Lima, C; Le Gouge, A; Dartigues, JF; Barberger-Gateau, P

doi: 10.1093/aje/kwm036pmid: 17369607

In the PAQUID (Personnes Ages Quid) study, the authors prospectively examined flavonoid intake in relation to cognitive function and decline among subjects aged 65 years or older. A total of 1,640 subjects free from dementia at baseline in 1990 and with reliable dietary assessment were reexamined four times over a 10-year period. Cognitive functioning was assessed through three psychometric tests (Mini-Mental State Examination, Benton's Visual Retention Test, Isaacs Set Test) at each visit. Information on flavonoid intake was collected at baseline. A linear mixed model was used to analyze the evolution of cognitive performance according to quartiles of flavonoid intake. After adjustment for age, sex, and educational level, flavonoid intake was associated with better cognitive performance at baseline (p 0.019) and with a better evolution of the performance over time (p 0.046). Subjects included in the two highest quartiles of flavonoid intake had better cognitive evolution than did subjects in the lowest quartile. After 10 years' follow-up, subjects with the lowest flavonoid intake had lost on average 2.1 points on the Mini-Mental State Examination, whereas subjects with the highest quartile had lost 1.2 points. This gradient persisted after adjustment for several other potential confounders. This study raises the possibility that dietary flavonoid intake is associated with better cognitive evolution.

Ramlau-Hansen, Cecilia Hst; Thulstrup, Ane Marie; Storgaard, Lone; Toft, Gunnar; Olsen, Jrn; Bonde, Jens Peter

doi: 10.1093/aje/kwm032pmid: 17369608

A few studies indicate that exposure to maternal smoking during fetal life decreases semen quality in adult life, but the results are inconsistent and retrospectively collected smoking data were used in most studies. From a Danish pregnancy cohort established in 19841987, 347 of 5,109 sons were selected according to their exposure to tobacco smoke in fetal life. From February 2005 to January 2006, a semen sample from the 347 men was analyzed for conventional semen characteristics according to standardized criteria by using a mobile laboratory. The authors found an inverse association between maternal smoking during pregnancy and total sperm count (p 0.002). Men exposed to more than 19 cigarettes daily during pregnancy had approximately 19% lower semen volume (p 0.04), 38% lower total sperm count (p 0.11), and 17% lower sperm concentration (p 0.47) compared with unexposed men. The odds ratio for oligospermia was 2.16 (95% confidence interval: 0.68, 6.87) among exposed men compared with the unexposed. No associations were found for sperm motility or morphology. These results indicate that prenatal exposure to tobacco smoke may have an adverse effect on semen quality and, if these associations are causal, they could explain some of the reported differences between populations and secular changes in semen quality.

Farr, Sherry L.; Schieve, Laura A.; Jamieson, Denise J.

doi: 10.1093/aje/kwm035pmid: 17351291

Approximately 30% of pregnancies in the United States may end in miscarriage or stillbirth. Whether pregnancies conceived through assisted reproductive technology (ART) are at an increased risk of loss is inconclusive, and data on maternal age-, ART type-, and gestational age-specific risk of loss are limited. Data on 148,494 ART pregnancies conceived from 1999 through 2002 were analyzed by use of the Kaplan-Meier method to estimate risks of pregnancy loss after specified gestational ages (conditional risk) for 14 groups stratified by maternal age and ART procedure. Births, maternal deaths, and induced abortions were censored. The Kaplan-Meier estimate of total risk of pregnancy loss was 29% but ranged from 22% to 63% depending on patient age and ART procedure. By 6 weeks' gestation, 58% of all pregnancy losses occurred. Conditional risk of pregnancy loss ranged from 10% to 45% at 6 weeks' gestation and from 2% to 7% at the first trimester; it was less than 2% after 20 weeks' gestation. Results can be used to counsel ART patients and inform future research on the etiology of pregnancy loss.

Rahman, Anisur; Vahter, Marie; Ekstrm, Eva-Charlotte; Rahman, Mahfuzar; Golam Mustafa, Abu Haider Mohammad; Wahed, Mohammad Abdul; Yunus, Mohammed; Persson, Lars-ke

doi: 10.1093/aje/kwm025pmid: 17351293

The authors evaluated the effect of arsenic exposure on fetal and infant survival in a cohort of 29,134 pregnancies identified by the health and demographic surveillance system in Matlab, Bangladesh, in 19912000. Arsenic exposure, reflected by drinking water history and analysis of arsenic concentrations in tube-well water used by women during pregnancy, was assessed in a separate survey conducted in 20022003. Data on vital events, including pregnancy outcome and infant mortality, were collected by monthly surveillance at the household level. The risk of fetal loss and infant death in relation to arsenic exposure was estimated by a Cox proportional hazards model. Drinking tube-well water with more than 50 g of arsenic per liter during pregnancy significantly increased the risks of fetal loss (relative risk 1.14, 95% confidence interval: 1.04, 1.25) and infant death (relative risk 1.17, 95% confidence interval: 1.03, 1.32). There was a significant dose response of arsenic exposure to risk of infant death (p 0.02). Women of reproductive age should urgently be prioritized for mitigation activities where drinking water is contaminated by arsenic.

Engel, Stephanie M.; Berkowitz, Gertrud S.; Barr, Dana B.; Teitelbaum, Susan L.; Siskind, Jodi; Meisel, Stefanie J.; Wetmur, James G.; Wolff, Mary S.

doi: 10.1093/aje/kwm029pmid: 17406008

Prenatal exposures to organophosphate pesticides and polychlorinated biphenyls have been associated with abnormal neonatal behavior and/or primitive reflexes. In 19982002, the Mount Sinai Children's Environmental Health Center (New York City) investigated the effects of indoor pesticide use and exposure to polychlorinated biphenyls on pregnancy outcome and child neurodevelopment in an inner-city multiethnic cohort. The Brazelton Neonatal Behavioral Assessment Scale was administered before hospital discharge (n 311). Maternal urine samples were analyzed for six dialkylphosphate metabolites and malathion dicarboxylic acid. A random subset of maternal peripheral blood samples from the entire cohort (n 194) was analyzed for polychlorinated biphenyls and 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene. Malathion dicarboxylic acid levels above the limit of detection were associated with a 2.24-fold increase in the number of abnormal reflexes (95% confidence interval: 1.55, 3.24). Likewise, higher levels of total diethylphosphates and total dialkylphosphates were associated with an increase in abnormal reflexes, as was total dimethylphosphates after paraoxonase expression was considered. No adverse associations were found with polychlorinated biphenyl or 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene levels and any behavior. The authors uncovered additional evidence that prenatal levels of organophosphate pesticide metabolites are associated with anomalies in primitive reflexes, which are a critical marker of neurologic integrity.

Lawlor, Debbie A.; Leon, David A.; Rasmussen, Finn

doi: 10.1093/aje/kwm028pmid: 17351292

The interpretation of the inverse association of birth weight with adult blood pressure after adjustment for concurrent size has been debated. In a large sample (n 378,707) of Swedish men aged 18 years, born between 1973 and 1984, the authors found considerable variation in birth weight within strata of identical adult body mass index (to the nearest kg/m2; range: 1733 kg/m2), weight (nearest kg; range: 52100 kg), and height (nearest cm; range: 164196 cm). The regression coefficient of systolic blood pressure on birth weight was inverse and the same within strata of identical body mass index (pinteraction 0.80), weight (p 0.79), and height (p 0.35). When the analyses were restricted to those who were born between 39 and 41 weeks' gestation, consistent inverse associations remained within strata of identical adult size. Findings were similar when hypertension (rather than mean systolic blood pressure) was the outcome. These findings demonstrate that, for male babies who grow to be the same size at age 18 years, those who were of lower birth weight have on average higher blood pressure and a greater risk of hypertension. They suggest that growth between conception and early adulthood has relevance to understanding the etiology and, hence, prevention of high blood pressure.