Association between antenatal corticosteroid exposure and respiratory morbidities in late preterm infants: a population-based study

OBJECTIVES: The clinical benefit of antenatal corticosteroids (ACS) in late preterm infants remains uncertain despite guideline expansion after the ALPS trial. This study evaluated the association between ACS exposure and respiratory outcomes in late preterm infants using a nationwide Korean cohort. METHODS: weeks) born between 2014 and 2022 were included. ACS exposure was defined as maternal betamethasone or dexamethasone administered within 7 days before delivery. Propensity scores based on maternal and neonatal characteristics were used to generate inverse probability of treatment weights. Relative risks (RRs) with 95 % confidence intervals (CIs) were estimated for respiratory outcomes. RESULTS: Among 53,529 infants, 6,294 (11.8 %) were exposed to ACS. Despite lower birth weight and gestational age in the ACS group, exposure was associated with reduced risks of ventilatory support (RR 0.923; 95 % CI 0.865-0.985), oxygen therapy (RR 0.827; 95 % CI 0.797-0.858), and respiratory distress syndrome (RR 0.908; 95 % CI 0.844-0.978). No significant differences were observed for transient tachypnea of the newborn (TTN) (RR 1.058; 95 % CI 0.991-1.129). Moderate-to-severe bronchopulmonary dysplasia (BPD) was rare and not associated with ACS. CONCLUSIONS: In this nationwide cohort, ACS exposure was associated with improved acute respiratory outcomes in late preterm infants, except for TTN and moderate-to-severe BPD, providing real-world evidence supporting its effectiveness.