Abstract
BACKGROUND: Thyroid autoimmunity (TAI) has been associated with the risk of recurrent pregnancy loss (RPL). This systematic review and meta-analysis was conducted to evaluate the influence of TAI on subsequent pregnancy outcome of women with RPL. METHODS: A systematic search of Medline, Web of Science, and Embase was conducted to identify studies evaluating the influence of TAI on subsequent risk of pregnancy loss (PL) in women with RPL. Study quality was evaluated via the Newcastle-Ottawa Scale. A random-effects model was utilized to pool the results, accounting for heterogeneity. RESULTS: Ten observational studies were included. Compared to women without thyroid autoantibodies, RPL women with TAI had a higher risk of PL in their subsequent pregnancy (risk ratio [RR]: 1.46. 95% confidence interval [CI]: 1.20 to 1.78, p < 0.001; I(2) = 35%). Sensitivity analyses showed consistent results in studies with thyroid peroxidase antibody positivity (RR: 1.50, 95% CI: 1.23 to 1.82) and in studies with TAI assessed before pregnancy (RR: 1.28, 95% CI: 1.07 to 1.53). Subgroup analyses showed that the results were not significantly different in prospective and retrospective studies, in RPL defined as at least two or three PL, in euthyroid women and women with euthyroidism or subclinical hypothyroidism, in women with and without levothyroxine treatment, in studies reporting first-trimester or overall PL, and in studies with different quality scores (p for subgroup difference all > 0.05). CONCLUSIONS: In women with RPL, positive for TAI may be related to a higher risk of PL in subsequent pregnancy.