Late-Preterm Antenatal Steroids for Reduction of Neonatal Respiratory Complications: A Randomized Controlled Trial.

Objective: To evaluate the efficacy of antenatal corticosteroids in reducing neonatal respiratory complications when administered to those at risk of preterm delivery between 34 and 36 6/7 weeks of gestation.

Methods: This was a single-center, triple-blind, randomized, placebo-controlled trial in southern India enrolling pregnant participants at risk of preterm delivery between 34 and 36 6/7 weeks of gestation. Computer-generated block randomization was used with participants randomized to either one course of intramuscular betamethasone or placebo. The primary outcome was a composite of treatment for respiratory distress in the neonate, defined as need for oxygen or continuous positive airway pressure or mechanical ventilation for at least 2 hours in the first 72 hours of life. Neonatal secondary outcomes were transient tachypnea of the newborn, respiratory distress syndrome, necrotizing enterocolitis, sepsis, hyperbilirubinemia, hypoglycemia, stillbirth, and early neonatal death; maternal secondary outcomes were chorioamnionitis, postpartum hemorrhage, puerperal fever, and length of hospitalization. All analyses were based on intention to treat. A sample size of 1,200 was planned with 80% power to detect a 30% reduction in rates of respiratory distress. After a planned interim analysis, enrollment was stopped for futility.

Results: From March 2020 to August 2022, 847 participants were recruited, with 423 participants randomized to betamethasone and 424 participants randomized to placebo. There were 22 individuals lost to follow-up. There was no statistically significant difference in the primary outcome (betamethasone 4.9% vs placebo 4.8%, relative risk 1.03, 95% CI, 0.57-1.84, number needed to treat 786). There were no statistically significant differences in secondary neonatal or maternal outcomes.

Conclusion: Betamethasone administered in the late-preterm period to those at risk for preterm delivery did not reduce the need for treatment of neonatal respiratory distress.

Clinical Trial Registration: Clinical Trials Registry of India, CTRI/2019/09/021321.