Teratology public affairs committee position paper: iodine deficiency in pregnancy.

Iodine deficiency is an important nutritional deficiency, with more than 2 billion people worldwide estimated to be at risk. The developing fetus and young children are particularly at risk. During pregnancy and lactation, iodine requirements increase, whether in iodine-poor or iodine-sufficient countries, making the mother and the developing fetus vulnerable. The American Thyroid Association (ATA) recommends 250 micrograms per day of iodine intake for pregnant and lactating women. The thyroid gland is able to adapt to the changes associated with pregnancy as long as sufficient iodine is present. Dietary intake is the sole source of iodine, which is essential to the synthesis of thyroid hormones. Iodine is found in multiple dietary sources including iodized salt, dairy products, seaweed, and fish. Prenatal vitamins containing iodine are a good source of iodine, but iodine content in multivitamin supplements is highly variable. Congenital hypothyroidism is associated with cretinism. Clinical hypothyroidism has been associated with increased risk of poor perinatal outcome including prematurity, low birth weight, miscarriage, preeclampsia, fetal death, and impaired fetal neurocognitive development. Subclinical hypothyroidism is also associated with poor pregnancy outcomes and potential fetal neurocognitive deficits, but the data are more variable than those for clinical hypothyroidism. We concur with the ATA recommendation that all pregnant and lactating women should ingest (through diet and supplements) 250 micrograms of iodine daily. To achieve this goal, we recommend that all pregnant and lactating women take daily iodine supplementation of 150 micrograms.