Effect of maternal iodine supplementation on thyroid function and birth outcome in goiter endemic areas

Abstract

Objective: The study was undertaken to examine the clinical and endocrine parameters of thyroid in a total of 460 pregnant women belonging to non-goiter areas (group 1; n = 156) and endemic areas without (group 2; n = 154) and with iodine supplementation (group 3; n = 150), and their respective newborns.

Methods: Women of group 3 with visible goiter were administered two capsules of iodized oil orally each containing 200 mg of iodine, from weeks 6--8 of pregnancy. Blood samples were obtained from all groups during each trimester, at parturition (umbilical cord blood) and after delivery. Serum triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) levels were measured by specific enzyme immunoassays.

Results: In group 2, serum T4 concentrations were low while T3 and TSH levels were high which showed hypothyroidism in the women of endemic areas. Goiter size decreased in most of the subjects who received a single dose of iodized oil and resulted in increase in serum concentrations of thyroid hormones; whereas, TSH levels decreased. Iodine supplementation also resulted in raised T4 and low TSH levels in the cord blood of neonates. During the course of study, two abortions, three still births and one cretin were reported in group 2; none was reported in group 3; and one still birth was reported in group 1.

Conclusions: The oral administration of a single dose of iodized oil is capable of correcting iodine deficiency both clinically and endocrinologically in mothers and neonates. Iodine supplementation has the potential to positively impact the birth weight of newborns.

Keywords: Endemic; Goiter; Iodine; Pregnancy; Thyroid.