During a 10-year period, 1977 to 1986, 233 (53%) of 442 inborn live births between 23 and 28 weeks' gestation survived; their 1-year survival rate was 7% at 23 weeks, 30% at 24 weeks, 31% at 25 weeks, 55% at 26 weeks, 67% at 27 weeks, and 71% at 28 weeks. No significant change in survival rate was observed over the years. Twelve percent of pregnancies and 20% of infants were multiple gestations. Singleton births had significantly higher survival rates compared with multiple births (58% versus 41%). The obstetric intervention rate, as measured by the frequency of cesarean section, increased significantly over the years: from 15% in 1977-1978 to 33% in 1985-1986. The neonatal intervention rate, as measured by the frequency of live births offered neonatal intensive care, remained unchanged. Ten percent were not treated: 4% had major malformations and 6% were considered "nonviable." Active perinatal management, which assumed fetal-neonatal viability, accounted for better survival rates compared with centers with a more passive management policy. Information on survival based on gestational cohorts plays an important role in helping obstetricians, neonatologists, and parents make appropriate management decisions.