Abstract Study question Are women with recurrent pregnancy loss (RPL) at higher risk of adverse perinatal outcomes in a subsequent pregnancy? Summary answer Women with a history of RPL have significant higher odds of adverse perinatal outcomes in a subsequent pregnancy. What is known already Studies have suggested that RPL women may have higher risks for obstetrical and perinatal complications such as hypertensive disorders, placental abruption, placenta accreta spectrum disorders, preterm delivery, and perinatal death in a subsequent pregnancy compared to those without an RPL history. However, the existing body of research presents a conflicting narrative, thus highlighting the need for a comprehensive understanding of the implications of RPL on pregnancy outcomes. Study design, size, duration A systematic review and meta-analysis was conducted. MEDLINE, EMBASE, Google Scholar and Cochrane databases were searched from inception until July 2023 for studies on RPL and adverse perinatal outcomes. Data was extracted by two independent reviewers. Participants/materials, setting, methods DerSimonian and Laird random effect meta-analyses were performed to pool effect estimates. Results were presented as odd ratios with their respective 95% confidence intervals. Subgroup analyses were conducted for those with unexplained RPL and by number of pregnancy losses. Sensitivity analysis using only high-quality studies and influence analysis were performed. The Newcastle-Ottawa Scale was used to assess for risk of bias. Main results and the role of chance The systematic search yielded 8,915 records, of which 42 studies (n = 5,619,124) were included in our meta-analysis. Women with RPL had higher odds of pre-eclampsia (OR 1.19; 95% CI, 1.03-1.37), pregnancy-induced hypertension (OR 1.24; 95% CI, 1.03-1.48), gestational diabetes (OR 1.76; 95% CI, 1.28-2.44), cesarean delivery (OR 1.65, 95% CI, 1.47-1.85), placental abruption (OR 1.57; 95% CI, 1.37-1.81), placenta previa (OR 1.93; 95% CI, 1.59-2.35; 7 studies), placenta accreta (OR 4.42; 95% CI, 3.09-6.33), preterm birth (OR 1.79; 95% CI, 1.65-1.93), very preterm birth (OR 2.58; 95% CI, 2.08-3.18), small for gestational age (OR 1.31; 95% CI, 1.15-1.78), congenital anomalies (OR 1.25; 95% CI, 1.02-1.53), stillbirth (OR 1.25; 95% CI, 1.04-1.51) and perinatal death (OR 2.04; 95% CI, 1.58-2.71) compared to women without a history of RPL. There was no association with aneuploidy. Limitations, reasons for caution Significant inter-study heterogeneity and inconsistent adjustment for confounders was noted across included studies. Wider implications of the findings RPL patients are at higher odds of adverse perinatal outcomes in a subsequent pregnancy, and therefore require additional counselling and monitoring in said pregnancy. There is an urgent need for further prospective research clarifying the relationship between RPL and perinatal outcomes. Trial registration number N/A
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