Iodine Nutrition During Pregnancy: Past, Present, and Future.

Iodine is a trace element that is important for the synthesis of thyroid hormones. During pregnancy, iodine requirements are increased by approximately 50% because of physiological changes. Adequate iodine status in pregnancy is crucial for maternal health and fetal growth. The World Health Organization (WHO) recommends a daily intake of 250 μg iodine for pregnant women to maintain adequate iodine status. Severe iodine deficiency during pregnancy can result in a series of detrimental effects on maternal and fetal health including hypothyroidism, goiter, stillbirth, abortion, increased neonatal mortality, neurological damage, and intellectual impairment. Correction of severe iodine deficiency can reduce the risk of adverse impacts. However, the influences of mild-to-moderate maternal iodine deficiency on fetal neural development and cognitive function are less clear. The safety and efficacy of iodine supplementation in mildly-to-moderately iodine-deficient women also remain uncertain. In addition, excess iodine during pregnancy carries a risk of adverse effects, and the recommended safe upper limits of iodine intake are controversial. Effective iodine supplementation should be implemented, and routine monitoring is necessary to guarantee adequate iodine status.