(279) Administration of and Delivery Timing after Antenatal Steroid Exposure: A Population-based Cohort Study

Antenatal steroids are administered to individuals at high risk for preterm birth to reduce the risk of neonatal respiratory morbidity. However, predicting who is at high risk for preterm birth is challenging. Our objective was to examine steroid administration practices by gestational age (GA) to inform potential strategies focused on its optimal use.

Study Design:

This was a retrospective cohort study of patients who delivered within a large health system between July 2016 and December 2023. Patients were included if they delivered a liveborn neonate ≥24 weeks of gestation. Data were obtained from the health system’s EHR. GA at the start of the first course of betamethasone was used in the comparisons. Any prior steroid exposure was reported by GA at delivery. For individuals who received antenatal steroids, we reported the percent who delivered within 7 days and who delivered at term by GA at steroid exposure.

Results:

Antenatal steroid administration was observed among 5,037 of 86,884 pregnant individuals (5.8%), including in 50.1% of 7,300 preterm births. Rates of prior steroid administration varied by gestational age at delivery (Figure 1), highest at 89.0% for deliveries between 32-33 completed weeks of gestation. 1.7% of all term deliveries had been exposed to betamethasone during pregnancy. Among those who received antenatal steroids, Figure 2 shows the percent delivered within 7 days, ranging from 22.6% at 24-27 to 67.2% at exposure 34-36 completed weeks of gestation. Across all exposure GAs, 25.1% of patients who received steroids ultimately delivered at term.

Conclusion: Antenatal steroid administration was not observed for 12.5% of births < 34 weeks of gestation and 66% of late preterm births. Conversely, only 38% of individuals received steroids and delivered in the upcoming week. This large cohort of deliveries demonstrates the challenges in optimally timing antenatal steroid administration. Future research should focus on identifying those at the highest risk for delivery who may receive the maximal benefit from appropriately timed steroid administration.