Effects of treating subclinical hypothyroidism in pregnancy in India: Are we treating too many for little gain? A retrospective cohort study.

Objective: To assess the impact of treatment of subclinical hypothyroidism (SCH) on short-term pregnancy outcomes.

Method: Data from 4526 consecutive women with singleton pregnancies who delivered between January 2015 and December 2017 were analyzed. SCH was defined as a thyroid-stimulating hormone (TSH) level between 2.5 and 10 mU/mL with normal free thyroxine. Of those with SCH, some were treated but others were not. These two groups were compared using χ and Student t tests for categorical and continuous variables, respectively. Multiple logistic regression models, adjusted for maternal age, body mass index, parity, gestation at TSH measurement, and gestational diabetes mellitus status, were used to investigate the effect of treatment on pregnancy and neonatal outcomes.

Results: In all, 1227 (27.1%) of 4526 women had SCH, of whom 393 (32.0%) were treated. The mean age and body mass index were similar in both groups. The mean gestation at measuring of TSH was 11.7 ± 6.5 weeks. There was no significant difference in pregnancy or neonatal outcomes between the two groups. A sub-group analysis when SCH was defined as TSH 4.0 mU/mL or greater showed a higher rate of large for gestational age and lower rates of low birth weight and small for gestational age in the treated group.

Conclusions: The prevalence of SCH based on the international guidelines threshold is high in India. Treatment of SCH did not show any difference in pregnancy and neonatal outcomes in this study.