Extensive studies in animal models on respiratory distress syndrome have demonstrated that antenatal administration of synthetic (dexamethasone) and natural (cortisol) corticosteroids accelerates lung maturation and significantly diminishes the occurrence of RDS. Although a variety of conditions in newborn infants have been treated with steroids over the past 20 years without adverse effects, investigations have been needed on the short-term effects of corticosteroids administered antenatally on neonate and mother and on the long-term effects on the infant.