Most obstetric interventions to reduce the morbidity and mortality of preterm birth are classified as tertiary interventions. These include regionalized perinatal care, treatment with tocolytic agents, antenatal corticosteroids, and antibiotics, and optimum timing of indicated preterm birth. Antenatal corticosteroids are often used to accelerate fetal lung maturity and reduce the risk of respiratory distress syndrome, intraventricular hemorrhage, and neonatal death.