Fetomaternal Outcome in Mothers with Subclinical Hypothyroidism: A Comparative Analytical Cohort Study

Abstract

Background: Thyroid dysfunction is the second most common endocrine disorder among women of reproductive age. SCH (Subclinical Hypothyroidism), characterized by elevated TSH (Thyroid-Stimulating Hormone) levels with normal FT4 (Free Thyroxine), has been associated with adverse maternal and fetal outcomes. Early identification and management during pregnancy may help improve pregnancy outcomes.

Methods: A comparative analytical cohort study was conducted in the Department of Obstetrics and Gynaecology, R.G. Kar Medical College and Hospital, from March 2023 to February 2024. Pregnant women diagnosed with subclinical hypothyroidism were compared with euthyroid pregnant women. Maternal outcomes, fetal outcomes, mode of delivery, thyroid function parameters, and neonatal outcomes were analyzed. Statistical analysis was performed to determine significant differences between the study and control groups.

Results: A total of 302 pregnant women were included in the study. Caesarean section was performed in 40.0% of SCH cases and 31.7% of controls. The mean TSH level was significantly higher in the SCH group (4.23±1.12 mIU/L) compared with controls (1.45±0.47 mIU/L; p<0.0001), whereas FT4 levels did not differ significantly. Gestational hypertension, premature rupture of membranes, and intrauterine growth restriction were significantly more common among mothers with SCH. The mean gestational age at delivery and mean birth weight were significantly lower in the SCH group than in controls.

Conclusion: Subclinical hypothyroidism during pregnancy is associated with an increased risk of adverse maternal and fetal outcomes, including gestational hypertension, PROM, IUGR, lower birth weight, and earlier delivery. Early screening, timely diagnosis, and appropriate management of SCH may reduce these complications and improve fetomaternal outcomes. Further large-scale prospective studies are recommended.