Prevalence of hypothyroidism among pregnant women and associated feto-maternal outcomes in India: Systematic review and meta-analysis.

Background and objectives Hypothyroidism is the most common thyroid disorder during pregnancy and, if not managed adequately, increases the risk of adverse foeto-maternal outcomes. The present systematic review and meta-analysis was conducted to assess the prevalence of hypothyroidism among Indian pregnant women and related foeto-maternal outcomes. Methods A systematic search was conducted across PubMed, Google Scholar, and preprint servers to identify observational studies reporting the prevalence of hypothyroidism and associated foeto-maternal outcomes among Indian pregnant women. A random-effects model was utilised to pool effect sizes, and heterogeneity was assessed using I2 statistic. Funnel plots, along with Begg's and Egger's tests, were used to assess publication bias. Data were analysed using STATA version 17. Results A total of 60 studies were included. The pooled prevalence of hypothyroidism among pregnant women was 17% [95% confidence interval (CI): 14%, 19%] with subclinical hypothyroidism at 15% (95% CI: 12%, 18%) and overt hypothyroidism at 3% (95% CI: 3%, 4%). In women with subclinical hypothyroidism, the pooled prevalence of adverse maternal outcomes was 9% (95% CI: 6%, 11%), while the prevalence of adverse foetal outcomes was 11% (95% CI: 9%, 14%). The pooled prevalence was 18% for preterm birth (95% CI: 11%, 25%), 17% for low birth weight (95% CI: 10%, 25%), 7% for intrauterine death (95% CI: 2, 14%), and 2% for stillbirth (95% CI: 0, 4%). Among women with overt hypothyroidism, the prevalence of adverse maternal and foetal outcomes was 12% (95% CI: 10%, 15%) and 14% (95% CI: 11%, 17%), respectively. The pooled prevalence was 22% for low birth weight (95% CI: 13%, 31%), 16% for preterm birth (95% CI: 9%, 24%), 16% for intrauterine death (95% CI: 7%, 27%), and 6% for stillbirth (95% CI: 1%, 13%). Most studies used trimester-specific TSH cut-offs based on the American Thyroid Association guidelines. One fourth (n=15) of the 60 studies applied alternative thresholds, with upper limits for normal TSH varying from 4.0-10.0 mIU/L. Interpretation and conclusions The rising burden and adverse consequences of hypothyroidism in pregnancy demand urgent attention. Uniform, evidence-based screening and management practices must be implemented at all levels of care. There is a pressing need for India-specific diagnostic cut-offs and large-scale prospective studies to inform treatment thresholds and long-term outcomes.