Timing of birth in multiple pregnancy

Timing of delivery of twins should be decided when the benefit of prolonging the pregnancy outweighs the risk of stillbirth. Perinatal mortality of singletons is increased significantly after 42 weeks, whereas perinatal mortality in twins starts to increase significantly after 37 weeks. Recent, large cohort studies have showed significantly higher stillbirth rates near term even in apparently low-risk monochorionic twin pregnancies. Stillbirth risk in monochorionic twins is three-fold higher than in dichorionic twins, and this risk remains high throughout the pregnancy. In uncomplicated monochorionic twins between 32 and 37 weeks, no statistically significant increase of stillbirth occurs between 32 and 37 weeks; these pregnancies are usually monitored until delivery at 37 weeks. The risk of stillbirth in dichorionic twins does not seem to be different between 28 and 38 weeks, justifying a differential policy for the timing of delivery in monochorionic compared with dichorionic twin pregnancies. Therefore, uncomplicated dichorionic twins should be managed expectantly, and delivery can be arranged from 38 weeks. In cases of discordant fetal wellbeing at preterm gestations, timing of delivery should be based mainly on parameters and outlook for the healthy twin balanced against the condition of the compromised fetus. The threshold for early delivery may be lower in monochorionic twins because of the high mortality and morbidity in surviving twins with co-twin death.