(593) Delayed Interval Delivery in Multiple Gestations at Periviability – A Multicenter Retrospective Cohort Study

Objective:
Delayed interval delivery (DID) is a rare strategy for preterm multiple gestations where delivery of the remaining fetus(es) is deferred following the delivery of the first infant, with the goal of improving outcomes for the retained fetuses. Clinical outcome data is limited due to the rarity of this scenario, which adds to the complexity of counseling patients who are considering DID. We sought to summarize contemporary obstetric care and neonatal outcomes in the setting of DID at periviability in a multicenter cohort.

Study Design:
This multicenter retrospective cohort study analyzed data on periviable births (22w0d-24w6d) from 13 institutions between 2010-2020. From this cohort, we obtained cases of delayed interval deliveries where data was available for the retained twin. Management and outcome data were compiled for all viable fetuses. Deliveries were then stratified by the viability of Twin A at delivery and neonatal outcomes were compared between the two groups.

Results:
13 pregnant persons and 20 infants from 6 institutions were included. All pregnancies were dichorionic-diamniotic twins who delivered from 2013-2019. The median intertwin delivery interval was 7.5 days (range 29 hours–5 weeks) and was longer when Twin A delivered before 22 weeks compared to after 22 weeks (median 14 days vs. 5 days 10 hours). When Twin A delivered liveborn between 22-24 weeks, survival was 80% (4/5) for Twin A compared to 87.5% (7/8) for Twin B among those with resuscitation. When Twin A delivered prior to 22 weeks and Twin B delivered periviable, there were no Twin B survivors (0/2) among those with resuscitation. The intraamniotic infection rate was 14.3% (1/7) in the Twin A group and 53.8% (7/13) in the Twin B group.

Conclusion:
In this multi-institutional, contemporary periviable cohort, DID has the potential to improve neonatal survival in the retained twin but is associated with a higher risk of intraamniotic infection. These findings contribute to the limited data on DID at periviability and may assist clinicians when counseling patients in this complex scenario.