US Incidence of Late-Preterm Steroid Use and Associated Neonatal Respiratory Morbidity After Publication of the Antenatal Late Preterm Steroids Trial, 2015-2017.

IMPORTANCE: The Antenatal Late Preterm Steroids (ALPS) trial demonstrated a 20% reduction in the risk of respiratory complications in neonates at risk for a late-preterm birth who were exposed to antenatal corticosteroids compared with those who were not.

OBJECTIVE: To assess whether new evidence of steroid administration for neonatal respiratory benefit in the late-preterm period is associated with changes in obstetric practice and the use of assisted ventilation for the neonate after delivery.

DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study of US births from February 1, 2015, to October 31, 2017, as ascertained from US natality data, included live-born, singleton neonates born between 34 and 36 completed weeks of gestation to people without pregestational diabetes. An interrupted time series analysis using Poisson regression models was conducted. Data were analyzed from July 11, 2022, to November 9, 2022.

EXPOSURES: Public dissemination of the ALPS trial results, which occurred during a 9-month period from February 1, 2016 (first published online), to October 31, 2016 (time of the last major professional society's guideline update in the months after the trial's publication).

MAIN OUTCOMES AND MEASURES: Steroid use, any assisted ventilation use, and assisted ventilation use for more than 6 hours immediately after the dissemination period.

RESULTS: A total of 707 862 births were included, divided among the 12-month predissemination period (n = 250 643), dissemination period (n = 195 736), and 12-month postdissemination period (n = 261 493). Most births were at 36 weeks of gestation (53.9% in the predissemination and postdissemination period; P = .10). Small but significant differences were found between the predissemination and postdissemination period cohorts: there were more individuals 35 years or older (19.5% vs 17.9%), fewer White individuals (67.8% vs 69.8%), and more publicly insured individuals (50.5% vs 50.1%) in the postdissemination period compared with the predissemination period, respectively (P < .001 for all). Compared with what rates were expected based on the predissemination trends, the adjusted rate of steroid use increased from 5.0% to 11.7% (adjusted incidence rate ratio [IRR], 2.34; 95% CI, 2.13-2.57), and assisted ventilation use decreased from 8.9% to 8.2% (adjusted IRR, 0.91; 95% CI, 0.85-0.98) after the dissemination period. No change was observed in assisted ventilation use for more than 6 hours (adjusted IRR, 0.98; 95% CI, 0.87-1.10).

CONCLUSIONS AND RELEVANCE: These findings suggest that there was an immediate change in practice of administering antenatal steroids and a reduction in neonatal morbidity among late-preterm births associated with the dissemination of the ALPS trial, suggesting that this evidence may be translating into a reduction in immediate respiratory morbidity outside the context of a clinical trial.