A Cochrane review included 12 studies with a total of 1557 women and 1661 infants. Dexamethasone decreased the incidence of intraventricular haemorrhage (IVH) compared with betamethasone (RR 0.44, 95% CI 0.21 to 0.92; 4 trials, 549 infants); however no statistically significant difference was seen for severe IVH (RR 0.40, 95% CI 0.13 to 1.24; 4 trials, 563 infants). No statistically significant differences were seen for other primary outcomes including respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia, perinatal death, or mean birthweight. Results for biophysical parameters were inconsistent, but mostly no important differences were seen for these, or any other secondary outcome except for neonatal intensive care unit (NICU) admission. In one trial of 105 infants, significantly more infants in the dexamethasone group were admitted to NICU compared with the betamethasone group (RR 3.83, 95% CI 1.24 to 11.87). Oral dexamethasone compared with intramuscular dexamethasone increased the incidence of neonatal sepsis (RR 8.48, 95% CI 1.11 to 64.93; 1 trial, n=183). Apart from a reduced maternal postpartum length of stay for women who received betamethasone at 12-hourly intervals compared to 24-hourly intervals in one trial (MD -0.73 days, 95% CI -1.28 to -0.18; 215 women), no differences in maternal or neonatal outcomes were seen between the different betamethasone dosing intervals assessed.
Comment: The quality of evidence is downgraded by imprecise results (limited study size for each comparison).