Prematurity is responsible for a greater fetal loss than are all other complications of the second and third trimesters of pregnancy and the neonatal period. A survey of 16,000 consecutive deliveries demonstrated a relationship between prematurity and various factors, including the mother's race and age, the maternal hemoglobin value, the time between pregnancies, a history of prematurity, and maternal heart size. Recommendations are made for the prevention of premature labor and for management of the newborn premature infant.