Low Dose Antenatal Corticosteroids for Late Preterm Delivery

Antenatal corticosteroids (ACS) are a type of steroid medication that is administered to pregnant women at risk of preterm birth in order to reduce the risk of respiratory distress syndrome (RDS) and other complications in the newborn. ACS were first demonstrated to be effective in a controlled trial conducted in the 1970s by Liggins and Howie, who used a combination of betamethasone at a dose of 12 mg given in two doses 24 hours apart. Since then, numerous randomized controlled trials and meta-analyses have shown that ACS can significantly reduce neonatal death, RDS, intraventricular hemorrhage, necrotizing enterocolitis, and the need for respiratory support and neonatal intensive care unit admission in preterm infants. ACS are now recommended for use in virtually all pregnancies at risk of preterm delivery between 24 and 34 weeks of gestation. The use of ACS in late preterm pregnancies (between 34 and 37 weeks) has also been studied, with mixed results. The largest study to date, the ALPS trial, found that ACS reduced composite adverse outcomes and respiratory morbidity in late preterm infants, but did not significantly reduce the risk of RDS or mortality. The American Congress of Obstetricians and Gynecologists has recommended the use of ACS in late preterm pregnancies, but with caution due to the potential for adverse effects such as hypoglycemia. Long-term follow-up studies are needed to evaluate the potential long-term effects of ACS in late preterm infants. In this the participants will be randomly assigned to receive either a full dose (12 mg) or a quarter dose (3 mg) of betamethasone, administered 24 hours apart. The main outcome measure of the study will be the incidence of respiratory problems or neonatal death within 72 hours of delivery in the two groups. The study is designed to determine if the reduced dose of betamethasone is non-inferior (i.e., not significantly worse) than the full dose in preventing respiratory problems in late preterm infants.