(1017) Practice Patterns in the Administration of Late Preterm Antenatal Corticosteroids Among Twin Gestations

Objective: Predicting preterm delivery is challenging, especially among twin pregnancies. We sought to evaluate the odds of delivering twin pregnancies within 2-7 days of antenatal corticosteroid (ACS) administration in the late preterm period (optimally timed), by delivery indication.

Study Design: This is a retrospective cohort study of twin pregnancies at risk for late preterm delivery (Jan 2013-Dec 2022) performed at a large tertiary care health system. Patients were included if they had non-anomalous twin gestations and received at least one dose of ACS in the late preterm period (34 0/7- 36 6/7 weeks). They were excluded if they received ACS previously or had pre-gestational diabetes. The cohort was stratified into two exposure groups: patients at risk for spontaneous preterm birth (sPTB; preterm labor or preterm pre-labor rupture of membranes) and patients at risk for clinician initiated late PTB (i.e., hypertensive disorders of pregnancy). The primary outcome was optimally timed ACS administration. Secondary outcomes included median time from ACS administration to delivery, delivery at < 2 days and > 7 days, and PTB. Multivariable logistic regression was used to calculate odds ratios (aORs) of the primary and secondary outcomes, adjusted for potential confounders.

Results: Of 166 eligible patients, 30 (18.1%) delivered within 2-7 days. 86 (51.8%) were at risk for sPTB, and 80 (48.2%) were at risk for a clinician initiated late PTB. Group demographics are described in Table 1. Compared to patients at risk for sPTB, those with a clinician initiated late PTB were more likely to have optimally timed administration (4.6% vs 32.5%; aOR 9.2, 95% CI 3.2, 33. 9). Patients at risk for sPTB were more likely to deliver < 2 days (aOR 0.19, 95% CI 0.08, 0.42), with a shorter latency to delivery (7.0 vs 45.7 hours) (Table 2).

Conclusion: In this cohort of twin gestations at risk for late PTB, those at risk for clinician initiated late PTB were more likely to deliver within the optimal time period compared to those at risk for sPTB. Further study is warranted to evaluate factors associated with delivery timing.