Objective: To determine outcomes, in terms of perinatal and early death, need for treatment, and morbidity at the time of discharge home, among extremely preterm infants.
Design: A prospective observational study of all infants with a gestational age (GA) of 22 to 27 completed weeks or a birth weight of 500 to 999 g who were born in Norway in 1999 and 2000.
Results: Of 636 births, 174 infants (27%) were stillborn or died in the delivery room, 86 (14%) died in the NICU, and 376 (59%) were discharged from the hospital. The risk of being registered as stillborn or not being resuscitated increased with decreasing GA below 25 weeks. The survival rates for all births and for infants admitted to a NICU were, respectively, 0% for <23 weeks, 16% and 39% for 23 weeks, 44% and 60% for 24 weeks, 66% and 80% for 25 weeks, 72% and 84% for 26 weeks, 82% and 93% for 27 weeks, and 69% and 90% for >27 weeks. For the survivors, days of mechanical ventilation decreased from a median of 37 days to 3 days and the proportion in need of oxygen at 36 weeks' postconceptional age decreased from 67% to 26% at 23 and 27 weeks' GA, respectively. At 40 weeks' postconceptional age, the respective figures were 11% and 6%. The proportion with retinopathy of prematurity (ROP) requiring treatment decreased from 33% for GA of 23 weeks to 0% for >25 weeks. Periventricular hemorrhage of more than grade 2 occurred for 6% of the survivors and significant periventricular leukomalacia occurred for 5%, with no significant association with GA. The proportion of survivors without severe neurosensory or pulmonary morbidity increased from 44% for 23 weeks' to 86% for 27 weeks' GA. Apart from ROP, the morbidity rate was not associated with GA.
Conclusions: The survival rate was high and the morbidity rate at discharge home was low in the present study, compared with previous population-based studies. With the exception of ROP, the morbidity rates among the survivors were not higher at the lowest GAs, possibly because withholding treatment was considered more acceptable for the most immature infants. The need for intensive care increased markedly for survivors with the lowest GAs.