Objective: We aimed to characterize risk factors for combined twin delivery and assess neonatal outcome. Methods: This was a retrospective cohort study of all women admitted for trial of labor (TOL) with twin gestation, in a single, tertiary, university-affiliated medical center. Eligibility was limited to gestations with twin A delivered vaginally. Results: During the study period, 44 263 women delivered in our center, of whom 1307 (2.9%) delivered twins. Overall, 221 out of 247 women (89.5%) undergoing TOL delivered twin A vaginally. Parturients who delivered twin B by cesarean delivery (n = 23) were compared with those delivered twin B vaginally (n = 198). Multivariate analysis demonstrated that risk factors combined delivery were included non-cephalic twin B at admission (aOR 11.5, 95% CI 3.8-34.9, p<0.001) or after delivery of twin A (aOR 17.7, 95% CI 6.6-47.2, p<0.001), and dichorionic-diamniotic (DCDA) twins (aOR 8.9, 95% CI 1.8-44.0, p = 0.008). Spontaneous version of a cephalic twin B was not found to increase the risk (above the baseline risk of non-cephalic twin B) for combined delivery. Combined delivery was associated with slightly higher risk for hemorrhagic-ischemic encephalopathy of twin B (4.3% versus 0%, p = 0.003). Conclusion: Non-cephalic twin B at admission or following delivery of twin A poses higher risk for combined delivery. Neonatal outcome of twin B following combined delivery are comparable with those of vaginal delivery.