Iodine For Pregnancy: To Give and If So How Much?

Clinical Practice for Iodine Supplementation during Preconception, Pregnancy, and Lactation Lags Behind Medical Society Recommendations

Written by Elise Eller PhD

Practitioners do not follow professional recommendations regarding iodine supplementation for women who are or may become pregnant, according to results from a survey-based study.

Despite the known role of iodine as a critical micronutrient in fetal brain development1,2 and that iodine status among pregnant women in the United States is considered mildly deficient,3 iodine supplementation for pregnant women does not appear to be a priority.

Guidelines from the key professional organizations recommend that women take prenatal vitamins containing 150-250 µg of iodine daily during preconception, pregnancy, and lactation. 4-6

“These data highlight a disconcerting lack of awareness about the importance of iodine nutrition in pregnancy on the part of US obestetrians and midwives,” said Elizabeth Pearce, MD, of the Boston University School of Medicine and one of the study authors.

“Medical societies including the American Thyroid Association, Endocrine Society, and American Academy of Pediatrics currently advocate 150 µg daily iodine supplementation for US women during preconception and while pregnant or breastfeeding. Educational efforts are urgently needed to ensure that patients and their providers are aware of these recommendations. Endocrinologists can play a valuable role in educating ob/gyn colleagues and our patients," said Dr. Pearce.

Practice Gap: Women Are Not Encouraged to Take Iodine Around Pregnancy

The survey, which was conducted to evaluate awareness of iodine nutrition among obstetricians and midwives in the United States and to determine current clinical practices regarding iodine supplementation recommendations, reflected that approximately 75% of practitioners do not recommend iodine supplements to women during preconception, pregnancy, and lactation or, if they do, the recommend amount stated in guidelines is not met.3

The vast majority (93%─98%) of practitioners reported that they recommend prenatal vitamins for women planning pregnancy, pregnant women, and lactating women, but only 20%─25% of providers said that they often or always recommend prenatal vitamins containing iodine.

Even among the providers who recommend iodine-containing supplements to their patients, most did not always suggest the recommended amount of 150 µg per day. Thirty-five to 59% of providers recommended 150 µg/d, depending on whether the time frame was preconception, pregnancy, or lactation, but 13%─24% recommended less (50 µg/d) and 20%─43% prescribed more (250 µg or more per day). When factoring in the number of providers who do not recommend iodine-containing supplements at all, only 10%─19% of obstetricians and midwives are prescribing the recommended 150 µg/d during preconception, pregnancy, and lactation.  

Lack of Awareness of Iodine Deficiency

Although approximately two-thirds of obstetricians and midwives knew that iodine deficiency in pregnant women might be harmful to the fetus, most providers were not aware that iodine status of pregnant women in the United States was considered deficient.3 Approximately 35% of obstetricians and 43% of midwives considered iodine status to be deficient, with 47% of obstetricians and 32% of midwives considering iodine status to be adequate and 13% of obstetricians and 15% of midwives saying they did not know.3

“This is an interesting and important article because understanding women’s nutritional needs is a critical part of conception and peripartum counseling,” Elena A. Christofides, MD, FACE of Endocrinology Associates in Columbus, Ohio, told EndocrineWeb. “Our female patients rely on their healthcare practitioners for accurate counseling and education about how to optimize a healthy pregnancy outcome. Assessing the level of understanding of those delivering care to this vulnerable population is the first step to addressing any health disparities that may exist. Once identified, any deficiencies must be addressed in order to ensure that our population has the best data for making informed decisions about their needs.”

However, Dr. Christofides did not completely agree with the study’s findings. “This article’s conclusions imply that those delivering care to our women lack understanding of this particular nutritional need. While the low rates of iodine supplementation recommendations seem disturbing at first glance, the authors make no mention of the rationale or reasoning behind these answers. If the aim of this study is to prove an educational deficiency necessitating intervention, then an understanding of the reasons behind these numbers would be relevant,” said Dr. Christofides.  “As such, I am glad to see behavioral work about healthcare delivery disparities but would caution overreliance on studies that do not fully elucidate the actual behavior being measured.”


1.     Ausó E, Lavado-Autric R, Cuevas E, et al. A moderate and transient deficiency of maternal thyroid function at the beginning of fetal neocorticogenesis alters neuronal migration. Endocrinology. 2004;145:4027-4047.

2.     Zimmerman MB, Boelaert K. Iodine deficiency and thyroid disorders. Lancet Diabetes Endocrinol. 2015;3:286-295.

3.     de Leo S, Pearce EN, Braverman LE. Iodine Supplementation in Women during Preconception, Pregnancy, and Lactation: Current Clinical Practice by U.S. Obstetricians and Midwives. Thyroid. Published online ahead of print. Oct 26, 2016. Accessed on October 30, 1016.

4.Leung AM, Pearce EN, Braverman LE, Stagnaro-Green A. AAP Recommendations on Iodine Nutrition During Pregnancy and Lactation. Pediatrics. 2014;135(4)

5.    American Thyroid Association Task Force on Thyroid and Pregnancy. Iodine needs in the pregnant and postpartum woman. Available at:

6.     Abalovich M, Amino N, Barbour LA, et al. A 2007 Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 92:S1–S47.

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