The birth of a baby before 37 completed weeks of pregnancy, which presents a greater risk of serious health problems.
Delivery occurring between 20 and 38 weeks’ gestation. Neonatal morbidity and mortality are high because of physiological immaturity. Preterm neonates are at high risk for developing respiratory distress syndrome; intraventricular hemorrhage; sepsis; patent ductus arteriosus; retinopathy of prematurity; and necrotizing enterocolitis.