Numerous investigations have indicated that antenatal corticosteroid administration reduces neonatal morbidity in preterm infants. Despite this, antenatal corticosteroid usage continued to be low on both sides of the Atlantic up to the late 1980s and early 1990s. Antenatal corticosteroid therapy finally came of age in 1995 with the publication of the National Institutes of Health Consensus Statement on effects of corticosteroids for fetal maturation on perinatal outcomes. The randomised trials of antenatal corticosteroid therapy have been based on the use of dexamethasone or betamethasone. However, observational evidence indicates differences in outcome, which may relate to the preparations themselves or to the preservatives included.