What is the success rate of trial of labor in monochorionic diamniotic twins? A systematic review and meta-analysis of observational studies

OBJECTIVE: This meta-analysis aimed to evaluate the success rate of trial of labor in monochorionic diamniotic pregnancies and the impact of delivery mode on neonatal outcomes. DATA SOURCES: Searches were performed in MEDLINE/PubMed, Embase, Scopus, Cochrane Central Register of Controlled Trials, ClinicalTrials.gov, and the International Clinical Trials Registry Platform from the inception of each database until April 2022. STUDY ELIGIBILITY CRITERIA: Selection criteria included observational studies analyzing the delivery mode among monochorionic diamniotic gestations. METHODS: All analyses were carried out using an intention-to-treat approach, evaluating women according to the delivery mode to which they were assigned in the original studies. RESULTS: Seventeen studies met the eligibility criteria and were suitable for qualitative and quantitative analysis. In total, 4116 women were analyzed. This meta-analysis showed that trial of labor in monochorionic diamniotic pregnancies resulted in vaginal delivery of both twins in 75.5% of cases (95% confidence interval, 69.1-80.9). Failure to deliver the second twin vaginally occurred in 3.8% of cases (95% confidence interval, 2.5-5.7). In addition, the neonatal outcomes were comparable among women with monochorionic diamniotic pregnancy undergoing different planned delivery modes. Neonatal death occurred in 3.7 per 1000 cases in the planned cesarean delivery group and in 1.6 per 1000 cases in the planned vaginal delivery group. Perinatal death was observed in 7.5 per 1000 cases in the planned cesarean delivery group and in 5.8 per 1000 cases in the planned vaginal delivery group. Umbilical artery pH <7.00 occurred in 0 per 1000 cases in the planned cesarean delivery and 4.6 per 1000 cases in the planned vaginal delivery group. Neonatal intensive care unit stay of >72 hours had a prevalence of 59.7 per 1000 cases in the planned cesarean delivery and 42.8 per 1000 cases in the planned vaginal delivery group. CONCLUSION: This meta-analysis showed that trial of labor in monochorionic diamniotic pregnancies is successful in most cases and relatively safe, considering that neonatal and perinatal mortality and severe morbidity were comparable between the trial of labor and planned cesarean delivery groups. Therefore, the choice of planned delivery mode in twin gestations should not be made a priori.