Antenatal hormone therapy for improving the outcome of the preterm infant.

The value of antenatal therapy with glucocorticoids in improving the pulmonary outcome of preterm human infants was first demonstrated in 1972. Accelerated lung maturation occurs with physiologic stress levels of corticosteroid by receptor-mediated induction of specific developmentally regulated proteins. Since the first report by Liggins, multiple controlled trials have demonstrated a decreased number of cases of respiratory distress syndrome and mortality in treated infants. In addition, prenatal therapy leads to decreased intraventricular hemorrhage and hospital costs, and there is strong evidence for decreased incidence of both patent ductus arteriosus requiring therapy and necrotizing enterocolitis. The recommendations of the 1994 National Institutes of Health Consensus Conference include use of antenatal corticosteroids in virtually all women who are in labor when the fetus is between 24 to 34 weeks' gestation. The combination of antenatal corticosteroids with thyrotropin releasing hormone holds promise for further reducing the incidence and severity of respiratory distress syndrome and decreasing chronic lung disease in the preterm infant.