Normal pregnancy results in a number of important physiological and hormonal changes that alter thyroid function. In pregnancy, the thyroid gland being subjected to physiological stress undergoes several adaptations to maintain sufficient output of thyroid hormones for both mother and fetus. Consequently, pregnant women have been found to be particularly vulnerable to iodine deficiency disorders (IDD), and compromised iodine status during pregnancy has been found to affect the thyroid function and cognition in the neonates.
Two decades after successful universal salt iodization (USI) in the country, there is scarce data on the iodine status of the pregnant women and their neonates. This is more relevant in areas like Kashmir valley part of sub-Himalayan belt, an endemic region for IDD in the past. The objective was to estimate Urinary Iodine status in pregnant women, the most vulnerable population.
Materials and Methods:
We studied thyroid function [free T3 (FT3), T3, free T4 (FT4), T4, thyroid stimulating hormone (TSH)] and urinary iodine excretion (UIE) in the 1st, 2nd, and 3rd trimesters and at early neonatal period in neonates in 81 mother–infant pairs (hypothyroid women on replacement) and compared them with 51 control mother–infant pairs (euthyroid).
Mean age of cases (29.42 + 3.56 years) was comparable to that of controls (29.87 + 3.37 years). The thyroid function evaluation done at baseline revealed the following: FT3 2.92 ± 0.76 versus 3.71 ± 0.54 pg/ml, T3 1.38 ± 0.37 versus 1.70 ± 0.35 ng/dl, FT4 1.22 ± 0.33 versus 1.52 ± 0.21 ng/dl, T4 9.54 ± 2.34 versus 13.55 ± 2.16 μg/dl, and TSH 7.92 ± 2.88 versus 4.14 ± 1.06 μIU/ml in cases versus controls (P > 0.01), respectively. The 2nd to 6th day thyroid function of neonates born to case and control mothers revealed T3 of 1.46 ± 0.44 versus 1.48 ± 0.36 ng/dl, T4 of 12.92 ± 2.57 versus 11.76 ± 1.78 μg/dl, and TSH of 3.64 ± 1.92 versus 3.82 ± 1.45 μIU/ml, respectively.
UIE was similar (139.12 ± 20.75 vs. 143.78 ± 17.65 μg/l; P = 0.8), but TSH values were higher in cases (7.92 ± 2.88) as compared to controls (4.14 ± 1.06). Although UIE gradually declined from 1st trimester to term, it remained in the sufficient range in both cases and controls. Thyroid function and UIE was similar in both case and control neonates.
We conclude that pregnant Kashmiri women and their neonates are iodine sufficient, indicating successful salt iodization in the community. Large community-based studies on thyroid function, autoimmunity, malignancies, etc., are needed to see the long-term impact of iodization.