Preterm Labor and Birth: Condition Information

What is preterm labor and birth?

The term (or length of time) of a normal human pregnancy is about 40 weeks (9.2 months). Labor that begins before 37 weeks of pregnancy is called preterm labor (or early labor). An infant born before 37 weeks of development in the uterus (pronounced YOO-ter-us) is considered a preterm birth.
Late-preterm birth refers to infants born from 34 weeks through 36 weeks of pregnancy. More than 70% of preterm infants are born during this time.¹
Many organs, including the brain, lungs, and liver, need the final weeks of pregnancy to fully develop. Even infants born slightly preterm are at greater risk than full-term infants, but the earlier the delivery, the more likely the risk of serious disability or death. Adverse health outcomes related to preterm birth include cerebral palsy (a group of nervous system disorders that affect control of movement and posture and limit activity), developmental delays, and vision and hearing problems. Preterm births also cause heavy emotional and economic burdens for families.²