Preterm infants are at risk of mortality and morbidity. Antenatal corticosteroids (ACS) reduce the risks of neonatal death and morbidities, such as respiratory distress syndrome.~The standard of care for pregnant people at risk of preterm birth includes 2 doses of Celestone to accelerate fetal lung maturity (total 24 mg in Canada, 22.8 mg in Australia). There are no published clinical trial data on the benefits or risks of a single dose of antenatal corticosteroid vs. standard double doses (Ninan et al JOGC 2020).~Pregnant people at 22 weeks and 0 days to < 34 weeks and 6 days' gestation at risk of preterm birth with a singleton or twin gestation who have received the first dose of Celestone and consented to the trial will be randomized to receive approximately 24 hours later either an experimental placebo injection (of normal saline) or the standard double dose of Celestone to determine whether the intervention is non-inferior for the primary outcome of a composite of perinatal mortality or substantial morbidity.
Antenatal corticosteroids (ACS) reduce the risks of neonatal death and morbidities in preterm infants, such as respiratory distress syndrome.~The standard of care for pregnant people at risk of preterm birth includes 2 doses of Celestone (for a total of 24 mg in Canada, or 22.8 mg in Australia) to accelerate fetal lung maturity.~The investigators plan to conduct a randomized controlled trial to determine whether half the usual dose (12 mg in Canada, or 11.4 mg in Australia) of Celestone is non-inferior to the standard double doses.