Impact of maternal thyroid dysfunction on fetal and maternal outcomes in pregnancy: a prospective cohort study

Background: Thyroid dysfunction in pregnancy can adversely impact maternal and fetal outcomes. However, the association between thyroid status and specific adverse outcomes needs clarity, especially in understudied regions.

Objective: This prospective cohort study aimed to illuminate the multifaceted associations between maternal thyroid dysfunction and feto-maternal outcomes in Gujarat, India.

Methods: This hospital-based cohort study recruited and monitored 500 euthyroid, 250 hypothyroid, and 150 hyperthyroid pregnant women until delivery. Maternal thyroid status was determined by serum thyroid stimulating hormone (TSH) and free thyroxine (fT4) levels. Adverse fetal outcomes included preterm birth, neonatal intensive care unit (NICU) admission, respiratory issues, and low APGAR scores. Maternal outcomes included preeclampsia, haemorrhage, hypertension, postpartum thyroiditis, and thromboembolism. Relative risks quantified associations between thyroid dysfunction and outcomes.

Results: Compared to euthyroid women, hypothyroid women had a higher RR for preterm birth (RR 1.8, 95% CI 1.1-3.0), low APGAR score (RR 2.5, 95% CI 1.5-4.1), preeclampsia (RR 3.0, 95% CI 1.9-4.8), postpartum haemorrhage (RR 1.6, 95% CI 1.2-2.1), and venous thromboembolism (RR 3.1, 95% CI 1.7-5.7). Hyperthyroid women had over twice the risk of low APGAR score (RR 1.8, 95% CI 0.9-3.5), neonatal hypoglycemia (RR 1.5, 95% CI 0.5-4.3), respiratory distress (RR 1.4, 95% CI 0.7-2.8), and postpartum thyroiditis (RR 2.3, 95% CI 1.1-4.8).

Conclusion: Maternal thyroid dysfunction escalates risks for adverse fetal and maternal outcomes. Thyroid monitoring and management during pregnancy are critical to mitigate complications.