The National Institute of Child Health and Human Development and the Office of Medical Applications of Research of the National Institutes of Health convened consensus conference in 1194 and 2000 that recommended giving a single course of corticosteriods to all pregnant women between 24 and 34 weeks of gestation who are at risk of preterm delivery within 7 days. Because of insufficient scientific evidence, the consensus panel also recommended that repeat corticosteroid courses, including so-called "rescue therapy," should not be routinely used but should be reserved for women enrolled in clinical trials. Betamethasone and dexamethasone have been most widely studied and have generally been the preferred corticosteroids for antenatal treatment to accelerate fetal organ maturation. The American College of Obstetricians and Gynecologists' Committee on Obstetric Practice supports the conclusions of the consensus conferences.