Extreme immaturity: outcome of 568 pregnancies of 23-26 weeks' gestation

To provide guidelines to the perinatologist regarding extremely premature infants based on the experience of the University of Toronto Newborn Service (two high-risk perinatal units and one outborn neonatal intensive care unit), with a catchment area of 60,000 deliveries annually.

The study included all births or admissions in the Newborn Service from January 1, 1982 to June 30, 1987 with gestational age determined by the best obstetric estimate of gestational age, ranging from 23-26 completed weeks. The obstetric records were reviewed and the surviving infants followed prospectively for a minimum of 2 years after delivery.

Analysis of the neonatal and 2-year follow-up data on 568 infants born between 23-26 weeks' gestation revealed a 39% mortality rate, which increased with decreasing gestation. The highest mortality rates occurred following complicated pregnancies, including fetal growth restriction. Intact survival increased with increasing gestational age, from 11% at 23 weeks to 50% at 26 weeks. There was a marked improvement in both mortality and morbidity by 25 completed weeks.

The results suggest that an aggressive approach before 24 completed weeks' gestation is not warranted. From a total of 60,000 live births per year, only one child born at 23 weeks' gestation and three at 24 weeks were free of major handicap at 2 years.