Antenatal steroids (ANS) are the most effective intervention in perinatal medicine, reducing neonatal death and respiratory distress syndrome (RDS) after preterm birth. A Cochrane review describes high certainty of evidence for a 22% reduction in neonatal death (relative risk (RR) 0.78, 95% CI 0.70 to 0.87) and a 28% reduction in RDS (RR 0.71, 95% CI 0.65 to 0.78). There is also evidence for a reduction in intraventricular haemorrhage (IVH) (RR 0.58, 95% CI 0.45 to 0.75), necrotising enterocolitis (NEC) (RR 0.50, 95% CI 0.32, 0.78) and developmental delay (RR 0.51, 95% CI 0.27 to 0.97).1

In the UK in 2022, 52% of women who delivered a baby between 23 and 33 weeks’ gestation received a full course of ANS within the week before delivery,2 which consists of 24 mg of either betamethasone or dexamethasone in divided doses over 24 hours, ideally completed 24 hours prior to birth.3 4 Given that the time leading up to preterm delivery is often busy, stressful and unpredictable there is an understandable desire to ‘complete’ perinatal optimisation (of which ANS is a key part) in less than 24 hours. In order to achieve this, it has been suggested that either a single dose of steroids could be given or the dosage interval could be reduced.

The BETADOSE study was a multicentre, randomised, double-blind, non-inferiority trial including 3141 participants.5 All participants received a first dose of betamethasone; 24 hours later women received a second dose (full-dose group) or a placebo (half-dose group). The primary outcome was RDS, which occurred in 20.0% of the half-dose …