Objective: This study aimed to explore the effects of levothyroxine on pregnancy outcomes and thyroid function in recurrent pregnancy loss (RPL) women with subclinical hypothyroidism (SCH) or thyroperoxidase antibody positivity (TPOAb+).
Methods: Literature search was performed from inception to 24 June 2022. The heterogeneity for each outcome was evaluated using Cochran's Q test and quantified with I-squared (I2). Pooled effect sizes were expressed as relative risk (RR) and weighted mean differences (WMD) with 95% confidence intervals (95% CIs). Stability of the results were assessed using the sensitivity analysis.
Results: Fifteen eligible studies with 1911 participants were included in this meta-analysis. The pooled data showed that levothyroxine decreased premature delivery rate (RR = 0.48, 95%CI: 0.32, 0.72), miscarriage rate (RR = 0.59, 95%CI: 0.44, 0.79), premature rupture of membranes (PROM) rate (RR = 0.44, 95%CI: 0.29, 0.66), and fetal growth restriction rate (RR = 0.33, 95%CI: 0.12, 0.89) in RPL women with TPOAb+. In RPL women with SCH, live birth rate was elevated (RR = 1.20, 95%CI: 1.01, 1.42) and miscarriage rate was reduced (RR = 0.65, 95%CI: 0.44, 0.97) by levothyroxine. In addition, levothyroxine substantially decreased TSH level (WMD = -0.23, 95% CI: -0.31, -0.16) and TPO level (WMD = -23.48, 95%CI: -27.50, -19.47).
Conclusions: Levothyroxine improved pregnancy outcomes and thyroid function in RPL women with TPOAb+ or SCH, indicating that levothyroxine may be beneficial for RPL women if TPOAb+ or SCH occurs. Future studies are needed to verify our findings.
Keywords: + SCH; Levothyroxine; TPOAb; pregnancy outcomes.