Clinical factors associated with combined delivery in twin gestations according to the presentation of the second twin

Abstract Purpose Combined twin delivery, defined as vaginal delivery of the first twin followed by cesarean delivery of the second twin, is associated with adverse neonatal outcomes. We evaluated presentation-stratified clinical and intrapartum factors associated with combined delivery. Methods This 13-year retrospective study included twin pregnancies with a vertex first twin in which the first twin was delivered vaginally. Pregnancies were stratified according to the presentation of the second twin before delivery of the first twin. Conventional multivariable logistic regression was used in the vertex–vertex group, whereas Firth penalized logistic regression was used in the vertex–nonvertex group because of the small number of outcome events and evidence of separation. Results Among 754 women, 565 had vertex–vertex and 189 had vertex–nonvertex pregnancies. Combined delivery occurred in 4.2% (24/565) and 9.0% (17/189), respectively ( p = 0.016). In vertex–vertex pregnancies, intrapartum presentation change of the second twin was associated with combined delivery (adjusted OR 5.12, 95%CI 1.97–13.30). In a separate model, maternal age > = 35 years (adjusted OR 1.98, 95%CI 1.01–3.91), multiparity (adjusted OR 4.52, 95%CI 1.54–13.24), and induction of labor (adjusted OR 3.14, 95%CI 1.64–6.01) were associated with presentation change. In vertex–nonvertex pregnancies, absence of epidural analgesia remained associated with combined delivery in a Firth model adjusted for gestational age < 32 weeks and intertwin birthweight discordance > = 20% (adjusted OR 4.45, 95%CI 1.51–14.41). Conclusion Presentation-stratified associations with combined delivery were predominantly intrapartum. Presentation change is an immediate intrapartum event rather than an antepartum predictor of combined delivery. The findings are most relevant to intrapartum preparedness rather than antenatal risk prediction.