Preterm Labor and Birth

In general, a normal human pregnancy lasts about 40 weeks, or just more than 9 months, from the start of the last menstrual period to childbirth. Labor that begins before 37 weeks is called preterm labor (or premature labor). A birth that occurs before 37 weeks is considered a preterm birth.

Preterm birth is the most common cause of infant death and is the leading cause of long-term disability related to the nervous system in children.

The NICHD is working both on its own and in collaboration with other agencies and organizations to learn more about the causes of preterm labor and birth, improve ways to predict which women are at risk for preterm delivery, and identify prevention methods to reduce the number of infants born early.

The NICHD also is studying ways to improve care for infants born too early in order to reduce death and disability associated with preterm birth.

Common Names

  • Early labor
  • Premature labor
  • Premature delivery
  • Premature birth
  • Preemie (for infant born preterm)

Medical or Scientific Name

  • Preterm labor
  • Preterm birth
  • Preterm infant
  • Late-preterm birth