What is the effect of intertwin delivery interval on the outcome of the second twin delivered vaginally?

Optimal management of twin deliveries is controversial. We aimed to assess if intertwin delivery interval, after vaginal delivery of the first twin, may have an influence on adverse neonatal outcomes of the second twin This is a retrospective observational study including diamniotic twin pregnancies with vaginal delivery of the first twin, between January 2000 and July 2017. Inclusion criteria were diamniotic pregnancies and vaginal delivery of the first twin. We excluded higher twin order, monoamniotic pregnancies, cesarean delivery of the first twin and patients with missing data. A number of 400 diamniotic twin pregnancies met the inclusion criteria and were divided, considering intertwin delivery interval into (1) ≤30 minutes ( = 365); and (2) >30 minutes ( = 35). Considering the two study groups, maternal and first twin characteristics and outcomes were similar. Second twin reported higher incidence of cesarean section and vacuum delivery, but similar incidence of neonatal adverse outcomes, in case of intertwin interval >30 minutes. At multivariate analysis, a difference between second and first twin weight ≥25% was correlated to neonatal adverse outcome, while we did not found this correlation with a cut-off of 30 minutes. In our study, growth discrepancy between twins was significantly correlated to adverse neonatal outcomes, while intertwin delivery time was not an influencing factor. So, in line with this result, in our clinical practice, we do not use a fixed time in which both twins should be delivered, neither in monochorionic nor in dichorionic pregnancies, when fetal wellbeing was demonstrated during labor.