(1120) Time interval from antenatal corticosteroid administration to delivery and severe neonatal morbidity

To evaluate the association between time interval from ACS administration to delivery and severe neonatal morbidity (SNM) among periviable, early, and late preterm births

Study Design: Retrospective cohort of singleton preterm births (PTBs) between 22 0/7-36 6/7 weeks’ gestational age (GA) at 2 tertiary academic medical centers from 2019-2022. All patients exposed to ACS prior to delivery were eligible for inclusion. Patients who had neonates that were not actively resuscitated, intrauterine fetal demise, and missing data were excluded. The primary outcome was SNM, a standardized composite neonatal adverse outcome indicator which includes diagnoses and procedures from the neonatal intensive care unit indicative of severe morbidity. Baseline characteristics and outcomes were compared by time interval from the first dose of ACS administration to delivery in 3 groups: < 2, 2-7, and >7 days. Multivariate logistic regression was performed to evaluate the association between the ACS timing and SNM within planned stratification by GA if there was evidence of interaction. Models were adjusted for potential confounders, and delivery within 2-7 days was as the reference group. Data were presented as adjusted odds ratios (aOR) with 95% confidence intervals (CI).

Results: Of the 2,367 patients included, 518 (21.9%) delivered after 2-7 days of ACS administration, 1,215 (51.3%) at < 2 days after ACS and 634 (26.8%) at >7 days after ACS. An interaction was noted between GA and time interval from ACS to delivery, where time interval from ACS to delivery was associated with more benefit in reducing SNM at earlier GA (P < 0.001). There was no association between ACS timing and SNM in PTBs occurring between 22 0/7-33 6/7 weeks (Table). Among late PTBs, ACS exposure < 2 days before delivery was associated with an increased risk of SNM (Table).

Conclusion: The likelihood of ACS administration occurring within 2-7 days of PTBs is low. ACS exposure < 2 days before delivery in the late preterm period was associated with an increased risk of SNM. Optimizing timing of ACS in the late preterm period requires further study.