Outcomes of the surviving co-twin after spontaneous single intrauterine demise in stage V twin-to-twin transfusion syndrome: A systematic review and meta-analysis

Objectives This review aims to estimate perinatal outcomes of co-twins following a single intrauterine fetal demise (IUFD) occurring in pregnancies complicated by spontaneous Stage V twin-to-twin transfusion syndrome (TTTS), focusing on gestational age at delivery, birth weight, and neonatal death. Methods We conducted a systematic review and single-arm meta-analysis following PRISMA guidelines and Cochrane methodology. PubMed, EMBASE, SCOPUS, Web of Science, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched up to March 2026. Eligible studies included spontaneous TTTS Stage V pregnancies with reported outcomes for the surviving co-twins. Pooled analyses were performed using random-effects models, while outcomes unsuitable for quantitative pooling were summarized narratively. Heterogeneity was assessed using I 2 statistics. Results Five studies including 32 surviving co-twins were included. The mean gestational age at birth was 29.96 weeks (95% CI 26.80 to 33.12), and the pooled neonatal mortality rate was 33.33% (95% CI 18.97 to 51.65). Birth weight was reported in three studies including 21 surviving co-twins, with mean values ranging from 616.67 to 1691.10 g across studies. Conclusion Stage V TTTS may be associated with prematurity, low birth weight, and high neonatal mortality rate. Given the very low certainty of evidence, findings should be interpreted as hypothesis-generating. Further prospective studies are needed to improve outcome counseling.