Maternal and infant morbidity following administration of repeat dexamethasone or betamethasone prior to preterm birth: A secondary analysis of the ASTEROID Trial

BACKGROUND: Clinical practice guidelines recommend administering antenatal corticosteroids (ACS), either betamethasone or dexamethasone, to women at risk of preterm birth at less than 35 weeks’ gestation. If women remain at risk of preterm birth seven or more days after an initial course of ACS, most guidelines recommend administration of a repeat dose(s). No randomised trials have assessed the efficacy of dexamethasone as a repeat steroid compared to betamethasone. AIM: We aimed to determine if there were differences between the use of dexamethasone or betamethasone as repeat ACS, for women who remain at risk of preterm birth after an initial course, on maternal, infant, and childhood health outcomes. METHODS: We performed a secondary analysis of data from the ASTEROID randomised trial, where women at risk of preterm birth were allocated to either betamethasone or dexamethasone. Infant, childhood, and maternal outcomes were compared according to whether women received a repeat dose(s) of dexamethasone or betamethasone. The primary outcome was a composite outcome of death or any neurosensory disability at age two years (corrected for prematurity). The ASTEROID trial is registered with ANZCTR, ACTRN12608000631303. RESULTS: 168 women and their infants were included, with 86 women receiving dexamethasone and 82 women receiving betamethasone as a repeat dose. Women in the two ACS groups had similar baseline characteristics. We observed little to no difference in the incidence of death or any neurosensory disability at age two years (OR 0.89, 95% CI 0.39 to 2.06, p = 0.79) or in the incidence of other infant, childhood, and maternal adverse health outcomes between women who received dexamethasone and those who received betamethasone. CONCLUSION: Use of dexamethasone for a repeat dose(s) compared to betamethasone did not result in any differences in infant, childhood, and maternal health outcomes. These results can be used to support clinical practice guideline recommendations.