ACOG practice bulletin. Management of preterm labor. Number 43, May 2003.

Preterm birth is the leading cause of neonatal mortality in the United States, and preterm labor precedes 40-50% of preterm births. Preterm birth accounts for 35% of all U.S. health care spending for infants and 10% of all such spending for children. Approximately 467,000 live births annually (11.5% of all live births) occur before term in the United States, and preterm births are responsible for three quarters of neonatal mortality and one half of long-term neurologic impairments in children. The purpose of this document is to present the various methods proposed to manage preterm labor and the evidence for their roles in clinical practice. Despite the numerous management methods proposed the incidence of preterm birth has changed little over the past 40 years (Fig. 1). Uncertainty persists about the best strategies for managing preterm labor.