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

OBJECTIVE

To evaluate the impact of recurrent pregnancy loss (RPL) on the risk of preterm birth (PTB) in subsequent pregnancies.

DESIGN

Systematic review and meta-analysis.

SETTING

Not applicable.

PATIENT(S): Pregnant women with and without a history of RPL.

INTERVENTION(S): PubMed, Embase, Google Scholar and Cochrane trial registry were used to identify relevant studies.

MAIN OUTCOME MEASURE(S): 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.

RESULT(S): 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.

CONCLUSION(S): 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.

CLINICAL TRIAL REGISTRATION NUMBER: CRD 224763.