Equivalence of Single and Standard Doses of Antenatal Corticosteroids for Late Preterm Neonatal Outcomes: Insights from a Secondary Analysis.

BACKGROUND: The recent paradigm shift of treating individuals at risk of late preterm birth with antenatal corticosteroids warrants an assessment of the effect of single dosage.

OBJECTIVE: To compare outcomes of neonates born in the late preterm period (34.0-36.6 weeks) following a single dose of antenatal corticosteroids versus placebo.

STUDY DESIGN: We performed a secondary analysis of the Antenatal Late Preterm Steroids (ALPS) trial (Gyamfi-Bannerman C. et al.). All individuals enrolled in the parent trial who received only a single dose of either antenatal corticosteroids or placebo and delivered within 24 hours were included. Primary outcome was a composite of respiratory support at 72 hr., including continuous positive airway pressure or high flow nasal cannula ≥ 2 h, oxygen with an inspired fraction of ≥ 30% for ≥ 4 h, or mechanical ventilation.

RESULTS: Of the 2,831 individuals in the parent trial, 1,083 (38.3%) met inclusion criteria; of them, 539 (49.8%) received a single dose of antenatal corticosteroids and 544 (50.2%) a single placebo dose. The placebo and antenatal corticosteroids groups had similar demographic and clinical characteristics. There was no difference in the rate of the primary respiratory outcome (aRR 1.12, 95% CI 0.85-1.47) or in the rate of respiratory distress syndrome (aRR 1.47, 95% CI 0.95-2.26) between those who received a single antenatal corticosteroids dose or placebo. An exploratory stratification by randomization-to-delivery intervals of 12-hour increments also showed no association with lower primary respiratory outcome rates.

CONCLUSION: In individuals with late preterm birth pregnancies who received antenatal corticosteroids and delivered before a second dose, there were no differences in neonatal respiratory morbidities compared to placebo.