Center for Prevention of Preterm Birth

About Preterm Labor

A typical full-term pregnancy lasts 37 to 42 weeks, calculated from the first day of your last menstrual period to childbirth. 

About 12 percent of all births in the United States are considered premature (occurring between 20 and 37 weeks). 

Most premature births happen without a known cause (spontaneous preterm labor). However, doctors are responsible for about one in four premature births for safety reasons.  In this case, labor is induced or Cesarean section delivery occurs before a baby is full term because of health concerns to the mother or baby. 

Medical Complications 

Many health and other problems after delivery have been associated with preterm delivery, such as:

  • Jaundice
  • Anemia
  • Infection
  • Apnea
  • Cerebral palsy
  • Patent ductus arteriosus
  • Respiratory distress syndrome
  • Intraventricular hemorrhage
  • Chronic lung disease
  • Retinopathy of prematurity
  • Temperature instability
  • Necrotizing enterocolitis
  • Seizures
  • Developmental delay
  • Learning difficulty
  • Neuromotor disability
  • Hearing loss
  • Behavioral problems

Important Facts


The rate of premature birth is higher now than 20 years ago despite technological and medical advances.

The most significant risk factor is a history of previous preterm delivery.

The  most  common  time  for  a  woman  to  deliver  a second premature child is during the  same week of pregnancy that the first child was delivered.

African-American women are at substantially higher risk to have a premature infant.