Preterm birth is the leading cause of neonatal mortality and the most common reason for antenatal hospitalization(1–4). In the United States, approximately 12% of all live births occur before term, and preterm labor preceded approximately 50% of these preterm births (5, 6). Although the causes of preterm labor are not well understood, the burden of preterm births is clear—preterm births account for approximately 70% of neonatal deaths and 36% of infant deaths as well as 25–50% of cases of long-term neurologic impairment in children (7–9). A 2006 report from the Institute of Medicine estimated the annual cost of preterm birth in the United States to be $26.2 billion or more than$51,000 per premature infant (10). However, identifying women who will give birth preterm is an inexact process.The purpose of this document is to present the various methods proposed to manage preterm labor and to review the evidence for the roles of these methods in clinical practice. Identification and management of risk factors for preterm labor are not addressed in this document.