Selective Reduction in Monochorionic Pregnancies With Selective Fetal Growth Restriction: A Systematic Review and Meta-analysis.

Abstract

Objective: To estimate the rates of co-twin intrauterine fetal demise (IUFD), co-twin neonatal demise, and gestational age (GA) at delivery in monochorionic (MC) pregnancies complicated by selective fetal growth restriction (sFGR) undergoing selective reduction (SR) and stratify the outcomes according to the surgical technique.

Data sources: PubMed, Embase, Cochrane Library, Scopus, and Web of Science were searched from inception through May 2026.

Study eligibility criteria: Studies were eligible if they reported MC pregnancies complicated by sFGR undergoing SR with data on co-twin IUFD or neonatal demise and GA at delivery.

Study appraisal and synthesis methods: This systematic review and meta-analysis was conducted per PRISMA guidelines and registered on INPLASY (INPLASY202580001). Pooled estimates were calculated using random-effects meta-analysis, and technique differences were evaluated using meta-analytic tests for subgroup differences. Post hoc binomial generalized linear mixed models (GLMMs) assessed the robustness of dichotomous outcomes without continuity correction. I² quantified heterogeneity across studies.

Results: A total of 22 studies, including 686 pregnancies, met the inclusion criteria and were eligible for quantitative synthesis. The overall rates of co-twin IUFD and co-twin neonatal death were 15% and 4%, respectively, and the GA at delivery was 35.4 weeks (95% CI, 34.2-36.6). In the primary indirect study-level subgroup analysis, pooled co-twin IUFD was higher in RFA than BCC studies (20% vs 9%; P=0.02). In the GLMM sensitivity analysis, the estimated rates remained higher in RFA than BCC studies (14.8% vs 6.6%), but the subgroup difference was not statistically significant (P=0.06). The only direct within-study comparison included 24 sFGR pregnancies and showed no significant difference in co-twin IUFD (BCC, 0/5; RFA, 3/19; P=1.00). Co-twin neonatal death rates were comparable (BCC, 5% vs RFA, 3%). GA at delivery was lower in cases undergoing BCC compared with RFA (34.5 weeks vs 36.8 weeks, respectively; P=0.039). These unadjusted comparisons may be confounded by differences in study and case characteristics.

Conclusions: In MC pregnancies complicated by sFGR undergoing SR, pooled risks of co-twin IUFD and neonatal death were approximately 15% and 4%, respectively. The primary analysis suggested lower co-twin IUFD and earlier delivery in BCC than RFA studies; however, the IUFD difference was not statistically significant in the GLMM sensitivity analysis, and all technique comparisons were indirect, unadjusted, potentially confounded , and the single direct comparison was small and inconclusive. Available evidence does not establish an advantage of BCC or RFA.