Neonatal hypoxia of the second twin after vaginal delivery of the first twin: what matters?

Optimal management of twin deliveries is controversial. We aimed to assess potential risk factors correlated to the development of hypoxia in the second twin after vaginal delivery of the first twin. This is a retrospective observational study including diamniotic twin pregnancies delivering at our Institution at 35 weeks of gestational age or more, weighing ≥1800 g. Hypoxia was defined as at least one of the following: Apgar score <5 at 10 minute, neonatal resuscitation for >10 minutes, neonatal acidosis (pH ≤7 and/or BE ≥12 mmol/L). A number of 275 diamniotic twin pregnancies met the inclusion criteria and were divided within the following groups: (1) second twin not developing neonatal hypoxia ( = 265); and (2) second twin developing neonatal hypoxia ( = 10). The rate of second twins with neonatal hypoxia during the study period was 3.6% (10/275). Abnormal cardiotocography during the intertwin delivery interval, defined as ACOG category III, was significantly correlated to second twin hypoxia. Of interest, there was no significant difference in the intertwin delivery interval between the study groups. In addition, breech presentation of the second twin did not show to be a risk factor for neonatal hypoxia. None of the second twins developing neonatal hypoxia was reported to have encephalopathy (follow up of at least 24 months). At multivariate analysis, only abnormal cardiotocography was an independent risk factor for second twin hypoxia (OR 17.8, 95% CI 4.1-77.2). In our study, neonatal hypoxia was significantly correlated to abnormal cardiotocography, while intertwin delivery interval was not correlated to the development of this adverse neonatal outcome.