Delaying delivery of the remaining fetus(es) in a multifetal pregnancy is feasible in some cases. However, the impact of this procedure on infant survival is unclear.

We used the US 1995-1998 Matched Multiple Birth File. We identified 200 twin pregnancies in which the first twin was delivered between 17 and 29 weeks of gestation and the second twin was delivered 2 or more days later. We individually matched the delayed deliveries with 374 twin pregnancies in which the second twin was delivered on the same or next calendar day. Perinatal outcomes and infant survival were compared between the delayed and nondelayed twins.

Among the 200 pregnancies with delayed delivery, the mean gestational age at first delivery was 23 weeks and the median duration of delay was 6 days (ranging from 2-107 days). One week of delay in delivery was associated with an increase in infant birth weight of 131 g on average (95% CI: 115-147 g). Moreover, 56% of the delayed second twins survived to 1 year of age, whereas only 24% of the nondelayed second twins survived to 1 year of age (P < .001). However, 11% of the second twin in delayed delivery (95% CI: 6%-16%) experienced fetal death before 24 weeks.

Delayed delivery of the remaining fetus(es) before 30 weeks of gestation for 2 or more days was associated with improved infant survival.