Equivalence of single and standard doses of antenatal corticosteroids for late preterm neonatal outcomes: insights from a secondary analysis

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.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.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.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.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.