Preterm birth after recurrent pregnancy loss: a systematic review and meta-analysis

To evaluate the impact of recurrent pregnancy loss (RPL) on the risk of preterm birth (PTB) in subsequent pregnancies.Systematic review and meta-analysis.Not applicable.Pregnant women with and without a history of RPL.PubMed, Embase, Google Scholar and Cochrane trial registry were used to identify relevant studies.The odds ratios (ORs) for the association between RPL and PTB across included studies were evaluated. Effect estimates were pooled using a DerSimonian and Laird random-effects meta-analysis model.Eighteen studies met the inclusion criteria. A total of 58,766 women with a history of RPL and 2,949,222 women without a history of RPL were included. A pooled OR of 1.60 (95% confidence interval [CI], 1.45-1.78; 18 observational studies; I2 = 85.6%) was observed in our random-effects meta-analysis. A trend toward higher odds of PTB is observed with the increasing number of pregnancy losses: 2 RPLs (pooled OR, 1.31; 95% CI, 1.09-1.57; I2 = 88.9%); ≥2 RPLs (pooled OR, 1.58; 95% CI, 1.27-1.96; I2 = 71.7%); and ≥3 RPLs (pooled OR, 1.81; 95% CI, 1.58-2.07; I2 = 73.6%). The analysis of the risk of PTB for patients with unexplained RPL demonstrated a significantly heightened risk of PTB in this subgroup (pooled OR, 2.05; 95% CI, 1.46-2.89; I2 = 21.0%). Inconsistent adjustment for confounders and significant between-study heterogeneity were noted in this study.Despite significant heterogeneity among studies, we found that women with a history of RPL had significantly higher odds of delivering preterm infants in subsequent pregnancies.CRD 224763.