Probability of Preterm Birth

Preterm birth (delivery before 37 weeks of gestation) affects approximately 10.5% of all births in the United States, or about 380,000 babies per year. Preterm birth is the leading cause of infant death and the leading cause of long-term neurological disabilities in children.

Risk factors include prior preterm birth (the single strongest predictor, increasing risk 2-3 fold), multiple gestation, short cervix, certain uterine or cervical abnormalities, infections, chronic conditions (hypertension, diabetes), smoking, substance use, inadequate prenatal care, short interpregnancy interval, and Black race (Black women have a preterm birth rate about 50% higher than White women).

Advances in neonatal intensive care have dramatically improved survival for preterm infants. Babies born at 28 weeks now have a survival rate exceeding 90%, and even babies born at 24 weeks survive about 60-70% of the time. Prevention strategies include progesterone supplementation for women with prior preterm birth, cervical cerclage for short cervix, and reducing elective early deliveries. Long-term outcomes vary widely, with the most premature babies at higher risk for cerebral palsy, learning disabilities, vision and hearing problems, and chronic health conditions.