Antenatal Steroid Exposure among Late Preterm Births Following Updated Clinical Guidance

In 2021, the Society for Maternal-Fetal Medicine updated its guidance on late preterm antenatal steroids, which included a recommendation to engage in shared decision-making on the risks and benefits. The objective of this study was to assess the effects of this updated guidance on the practice among a contemporary cohort of US births.

This retrospective cohort study implemented an interrupted time series (ITS) design among late preterm singleton births using encounter-level inpatient data from the Premier Healthcare Database (PHD). A 3-year observational period before (January 1, 2019, to December 31, 2021) and after (January 1, 2022, to December 31, 2024) the intervention date (selected as January 1, 2022) was defined to quantify whether the guideline was associated with changes in obstetric practice. Steroid exposure was modeled at the patient level as a binary outcome using Poisson regression with a log-link function, with a linear spline at the intervention knot to estimate both the pre-intervention slope and the change in slope following guideline dissemination. The change in slope at the knot was the primary parameter of interest. Time was measured in quarters. Incidence rate ratios can be interpreted as quarter percent changes (QPCs) in the rate of ACS use and are presented with 95% confidence intervals (CIs). RESULTS: 342,925 late preterm deliveries were included in the analysis: 176,938 in the pre-period and 165,987 in the post-period. 57,372 (32.4%) in the pre-period were exposed to late preterm steroids, and exposure rates were stable over time (adjusted QPC (aQPC) 1.01; 95% CI: 1.00, 1.01). Following guideline dissemination, steroid exposure rates declined by 3% per quarter (aQPC 0.97; 95% CI: 0.96, 0.98), indicating a significant change in the trajectory of steroid use among the population targeted by the guideline. In quarter 4 of 2024 (the end of the study period), the exposure rate decreased to 25.1%.

Late preterm steroid exposure decreased significantly after SMFM updated its clinical guidance, which newly highlighted the conflicting long-term data and recommended shared decision-making about the risks and benefits. Future research on the long-term risks and benefits of ACS is needed to inform clinical practice guidelines and shared decision-making.

Following SMFM's 2021 updated guidance on late preterm antenatal corticosteroids, which highlighted uncertain long-term neurodevelopmental risks and recommended individualized counseling, steroid exposure among late preterm births declined by approximately 3% per quarter in a nationally representative US cohort.