Effect of iodine supplementation during pregnancy on neonatal thyroid stimulating hormone

Background Thyroid hormone is essential for neurological development, particularly in the developing brain. Iodine is the important constituent of thyroid hormone. Its requirement during pregnancy is increased. Elevated neonatal thyroid stimulating hormone (TSH) is a sensitive indicator of iodine insufficiency in pregnant women. Our previous study in the year 2000 demonstrated that median urine iodine (UI) concentration in pregnant women was 85 μg/ L, a level of which indicates mild iodine deficiency. Since October 2010, Thai national universal iodine supplementation program has been started by prescribing a 150 μgiodine tablet daily to all pregnant women throughout their gestation. We, therefore, aimed to determine the effect of maternal iodine supplementation on neonatal TSH.