Guidelines for Iodine Nutrition Before, During, After Pregnancy

Pregnant woman holding pills
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According to the 2011 "Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum," during pregnancy, a woman's need for iodine is higher than when not pregnant.

Why Iodine is Important During Pregnancy

Iodine is needed specifically to help a woman increase her thyroid hormone production during pregnancy, as well as to meet the fetal need for iodine.

A fetus' thyroid gland does not start producing hormone until the second trimester of pregnancy, so sufficient iodine levels in a woman pre- and post-conception are essential for healthy neurological development in a developing baby.

In a woman who has sufficient iodine levels, typically the body will adapt to the increased need of iodine during pregnancy, and while breastfeeding.

But if a woman has even mild or moderate iodine deficiency, iodine levels typically decline throughout the pregnancy. Even mild to moderate degrees of iodine deficiency can increase the risk of maternal and fetal goiter (thyroid enlargement), as well as cognitive problems attention deficit and hyperactivity disorders (ADHD) and autism in children.

Consequences of Iodine Deficiency

Severe iodine deficiency, however, is a serious health crisis. Severe iodine deficiency is the leading cause of preventable mental retardation in the world today.

Severe iodine deficiency in pregnant women is linked to a substantially increased risk of miscarriage, stillbirth, premature birth, and increased perinatal and infant mortality, as well as developmental problems in children, including cretinism - a condition that can involve severe mental retardation, deaf-mutism, and motor function problems.

According to studies, while the U.S. population typically is iodine sufficient, women of childbearing age are the subset of Americans who are most likely to have low iodine levels. Throughout the world, iodine deficiency affects over 2.2 billion people and is most prevalent in South Asia, East Asia Pacific, and the East and South African regions.

In regions with severe iodine deficiency, pre-conception iodine supplementation has resulted in significantly improved cognitive performance for children and has greatly reduced the risk of cretinism and other severe complications, including stillbirth, and neonatal and infant mortality.

In mild to moderately iodine-deficient women, studies have shown that supplementation improved outcomes for children. The key benefits seem to occur if the iodine supplementation begins prior to conception, or occurs during the first 10 weeks of gestation -- that period when the fetus is unable to produce thyroid hormone. The benefits appear to drop off if supplementation begins after 10 to 20 weeks of gestation.

The Guidelines recommend that all pregnant and lactating women get a minimum of 250 mg iodine daily, and to accomplish that, pregnant women should supplement their diet with a daily oral supplement that contains 150 mg of iodine, in the form of potassium iodide.

Check Your Vitamin Labels

AN IMPORTANT NOTE: It should be noted that only about half the prenatal vitamins available in the U.S. - including prescription prenatal vitamins - contain iodine. Women should carefully check the labels of any prescription or over-the-counter prenatal vitamins to ensure they contain the sufficient level of iodine necessary to meet the Guidelines' recommendations.

To avoid the effects of excess iodine, the Guidelines point to the Institute of Medicine, which has defined the tolerable upper limit for daily iodine intake as 1100 mg/d (1.1 g/d) in all adults, including pregnant women.

They recommend that pregnant women avoid sustained iodine intake from diet and dietary supplements that exceeds 500 to 1100 mg daily, to avoid concerns about fetal hypothyroidism.

Other Sources of Iodine

In addition to diet and iodine supplements, pregnant women should be aware that there are other sources of iodine, including the heart drug amiodarone, which contains 75 mg iodine per 200 mg tablet, and iodine-based contrast agents used for medical tests, which can contain up to 380 mg of iodine per milliliter.


Stagnaro-Green, Alex, et. al. "Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum." Thyroid. Volume 21, Number 10, 2011 (Online)

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