Fetal reduction from twin to singleton gestation: A meta-analysis

Objective: To evaluate outcomes of fetal reduction in twin pregnancy. Search strategy: PubMed, EMBASE, Cochrane Central Register of Controlled Trials, and Google Scholar were searched from 1980 through December 2020. Selection criteria: Prospective or retrospective studies of pregnant women with twin gestations who had a transabdominal reduction of twin to singleton pregnancy with a comparison group of ongoing twin gestations. Data collection and analysis: Outcomes were meta-analyzed only if reported in at least three studies. Main results: Six studies with a pooled sample of 2867 women with a twin pregnancy of whom 624 underwent 2-to-1 reduction and 2243 did not. In the fetal reduction group, the odds of preterm birth before 34 and 37 weeks of pregnancy were lower by 36% (odds ratio [OR] 0.64, 95% confidence interval [CI] 0.48–0.86, P < 0.003) and 77% (OR 0.23, 95% CI 0.12–0.44, P < 0.001), respectively, than in the control group, and the odds of hypertensive disorders and cesarean delivery were lower by 75% (OR 0.25, 95% CI 0.15–0.43, P < 0.001) and 65% (OR 0.35, 95% CI 0.20–0.62, P < 0.001), respectively. Conclusion: Twin reduction to singleton pregnancy decreased the possibility of preterm birth, hypertensive disorders in pregnancy and cesarean delivery. Sufficiently powered prospective studies are needed to support these findings.