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Iodine Supplements During and After Pregnancy

Iodine Supplements During and After Pregnancy To the Editor: Dr Stagnaro-Green and colleagues1 argued that a randomized controlled trial (RCT) of iodine in pregnancy would be unethical because many international bodies recommend additional iodine intake, largely for the prevention of cognition-related adverse effects in offspring. We dispute their assertion that such a trial is necessarily unethical. While in regions of severe iodine deficiency, the benefit of iodine supplementation during pregnancy is indisputable, in regions of mild-to-moderate deficiency, the evidence for benefit is only suggestive.2 Previous RCTs of iodine in pregnancy in such regions lacked cognitive outcomes and only 2 small intervention studies, neither of which was randomized or placebo-controlled, afforded evidence of improvements in child cognition.2 Partly because of this lack of evidence, the United Kingdom does not recommend increasing iodine intake or supplementing with iodine during pregnancy or lactation despite recent findings of mild iodine deficiency in 14- to 15-year-old adolescent girls in 9 areas of the United Kingdom.3 Because the United Kingdom has no salt iodization policy, a woman's iodine intake is entirely dependent on her food choices, which may exclude good sources such as fish and milk. There may also be negative implications for fetal brain development in women with mild-to-moderate iodine deficiency who begin iodine supplementation during pregnancy; for example, a higher risk of thyroid failure was found in such women compared with those who had used iodized salt for several years.4 Furthermore, iodine supplementation at a dose of 150 μg/d or greater in a region of mild deficiency was associated with lower psychomotor scores in offspring than was a lower dose.5 These studies were limited by their observational nature and by iodine being a component of a multinutrient supplement, but they imply that evidence of a lack of harm, in addition to benefit, from a well-conducted RCT will be required for a change in the UK policy. Because the United Kingdom may be the only Western country with no recommendation for a higher intake of iodine or recommendation for iodine supplementation during pregnancy and lactation, and a no salt iodization policy, it is one of the few countries that could conduct a high-quality RCT capable of investigating whether iodine supplementation is beneficial in individuals with mild iodine deficiency. Back to top Article Information Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and reported being members of the UK Iodine-Status Strategy Group. Dr Bath reported receiving payment for lectures from the Dairy Council Northern Ireland and a PhD studentship from Wassen International. Dr Jolly reported a grant application to the UK National Institute for Health Research to undertake an RCT of iodine supplementation. Dr Rayman reported a grant to her institution from Wassen International to support a PhD studentship. References 1. Stagnaro-Green A, Sullivan S, Pearce EN. Iodine supplementation during pregnancy and lactation. JAMA. 2012;308(23):2463-246423288022PubMedGoogle ScholarCrossref 2. Pearce EN. What do we know about iodine supplementation in pregnancy? J Clin Endocrinol Metab. 2009;94(9):3188-319019734447PubMedGoogle ScholarCrossref 3. Vanderpump MP, Lazarus JH, Smyth PP, et al; British Thyroid Association UK Iodine Survey Group. Iodine status of UK schoolgirls: a cross-sectional survey. Lancet. 2011;377(9782):2007-201221640375PubMedGoogle ScholarCrossref 4. Moleti M, Di Bella B, Giorgianni G, et al. Maternal thyroid function in different conditions of iodine nutrition in pregnant women exposed to mild-moderate iodine deficiency. Clin Endocrinol (Oxf). 2011;74(6):762-76821521276PubMedGoogle ScholarCrossref 5. Murcia M, Rebagliato M, Iñiguez C, et al. Effect of iodine supplementation during pregnancy on infant neurodevelopment at 1 year of age. Am J Epidemiol. 2011;173(7):804-81221385833PubMedGoogle ScholarCrossref http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA American Medical Association

Iodine Supplements During and After Pregnancy

Bath, Sarah C.; Jolly, Kate B.; Rayman, Margaret P.
JAMA , Volume 309 (13) – Apr 3, 2013
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Iodine Supplements During and After Pregnancy

Abstract

To the Editor: Dr Stagnaro-Green and colleagues1 argued that a randomized controlled trial (RCT) of iodine in pregnancy would be unethical because many international bodies recommend additional iodine intake, largely for the prevention of cognition-related adverse effects in offspring. We dispute their assertion that such a trial is necessarily unethical. While in regions of severe iodine deficiency, the benefit of iodine supplementation during pregnancy is indisputable, in regions of...
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References (6)

Publisher
American Medical Association
Copyright
Copyright © 2013 American Medical Association. All Rights Reserved.
ISSN
0098-7484
eISSN
1538-3598
DOI
10.1001/jama.2013.2237
Publisher site
See Article on Publisher Site

Abstract

To the Editor: Dr Stagnaro-Green and colleagues1 argued that a randomized controlled trial (RCT) of iodine in pregnancy would be unethical because many international bodies recommend additional iodine intake, largely for the prevention of cognition-related adverse effects in offspring. We dispute their assertion that such a trial is necessarily unethical. While in regions of severe iodine deficiency, the benefit of iodine supplementation during pregnancy is indisputable, in regions of mild-to-moderate deficiency, the evidence for benefit is only suggestive.2 Previous RCTs of iodine in pregnancy in such regions lacked cognitive outcomes and only 2 small intervention studies, neither of which was randomized or placebo-controlled, afforded evidence of improvements in child cognition.2 Partly because of this lack of evidence, the United Kingdom does not recommend increasing iodine intake or supplementing with iodine during pregnancy or lactation despite recent findings of mild iodine deficiency in 14- to 15-year-old adolescent girls in 9 areas of the United Kingdom.3 Because the United Kingdom has no salt iodization policy, a woman's iodine intake is entirely dependent on her food choices, which may exclude good sources such as fish and milk. There may also be negative implications for fetal brain development in women with mild-to-moderate iodine deficiency who begin iodine supplementation during pregnancy; for example, a higher risk of thyroid failure was found in such women compared with those who had used iodized salt for several years.4 Furthermore, iodine supplementation at a dose of 150 μg/d or greater in a region of mild deficiency was associated with lower psychomotor scores in offspring than was a lower dose.5 These studies were limited by their observational nature and by iodine being a component of a multinutrient supplement, but they imply that evidence of a lack of harm, in addition to benefit, from a well-conducted RCT will be required for a change in the UK policy. Because the United Kingdom may be the only Western country with no recommendation for a higher intake of iodine or recommendation for iodine supplementation during pregnancy and lactation, and a no salt iodization policy, it is one of the few countries that could conduct a high-quality RCT capable of investigating whether iodine supplementation is beneficial in individuals with mild iodine deficiency. Back to top Article Information Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and reported being members of the UK Iodine-Status Strategy Group. Dr Bath reported receiving payment for lectures from the Dairy Council Northern Ireland and a PhD studentship from Wassen International. Dr Jolly reported a grant application to the UK National Institute for Health Research to undertake an RCT of iodine supplementation. Dr Rayman reported a grant to her institution from Wassen International to support a PhD studentship. References 1. Stagnaro-Green A, Sullivan S, Pearce EN. Iodine supplementation during pregnancy and lactation. JAMA. 2012;308(23):2463-246423288022PubMedGoogle ScholarCrossref 2. Pearce EN. What do we know about iodine supplementation in pregnancy? J Clin Endocrinol Metab. 2009;94(9):3188-319019734447PubMedGoogle ScholarCrossref 3. Vanderpump MP, Lazarus JH, Smyth PP, et al; British Thyroid Association UK Iodine Survey Group. Iodine status of UK schoolgirls: a cross-sectional survey. Lancet. 2011;377(9782):2007-201221640375PubMedGoogle ScholarCrossref 4. Moleti M, Di Bella B, Giorgianni G, et al. Maternal thyroid function in different conditions of iodine nutrition in pregnant women exposed to mild-moderate iodine deficiency. Clin Endocrinol (Oxf). 2011;74(6):762-76821521276PubMedGoogle ScholarCrossref 5. Murcia M, Rebagliato M, Iñiguez C, et al. Effect of iodine supplementation during pregnancy on infant neurodevelopment at 1 year of age. Am J Epidemiol. 2011;173(7):804-81221385833PubMedGoogle ScholarCrossref

Journal

JAMA – American Medical Association

Published: Apr 3, 2013

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