Effect of Autoimmune Thyroid Disease on Pregnancy Outcomes: A Systematic Review and Meta-Analysis

Background: Autoimmune thyroid disease (AITD) is common in women of reproductive age and is characterized by thyroid-specific autoantibodies, mainly TPOAbs and TgAbs. Its impact on pregnancy outcomes is not fully understood. However, evidence suggests a potential association with adverse maternal and neonatal outcomes. Objective: To assess the association between AITD and adverse pregnancy outcomes and evaluate the effect of levothyroxine (LT4) therapy in high-risk populations. Methods: A systematic search of PubMed and Web of Science was performed per PRISMA guidelines. Randomized controlled trials (RCTs) on pregnancy outcomes in women with AITD were included. Primary outcomes were preterm delivery, miscarriage, and live birth; secondary outcomes included maternal and neonatal complications. Risk of bias was assessed using RoB 2.0, and pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. Results: Eight RCTs with TPOAb-positive euthyroid or subclinical hypothyroid women were included. AITD increased preterm delivery risk (pooled OR 3.92, 95% CI 2.54–6.05). Miscarriage risk showed high heterogeneity (pooled OR 1.27, 95% CI 0.16–9.82). LT4 reduced miscarriage (pooled OR 0.52, 95% CI 0.34–0.80) and preterm delivery (pooled OR 0.37, 95% CI 0.17–0.80). Live birth rates favored LT4 but were not statistically significant. Maternal and neonatal complications were inconsistently reported. Conclusions: AITD is associated with higher preterm delivery risk. LT4 in high-risk women may reduce miscarriage and preterm birth. Further RCTs should stratify by AITD subtype, antibody titer, and thyroid function, and report perinatal outcomes systematically.