Aims: To assess whether lung function in late childhood had improved in subjects born extremely prematurely in the early 1990s compared to the early 1980s, and whether neonatal factors in the respective periods had different impact on long-term pulmonary outcome.
Design: Population-based, controlled cohort study. Lung function was determined in 81 of 86 (94%) eligible subjects born with gestational age < or =28 weeks or birthweight < or =1000 g in Western Norway in 1982-85 (n=46) and 1991-92 (n=35), and in 81 matched control subjects born at term.
Results: The incidence of bronchopulmonary dysplasia was similar in the two periods. At follow-up, airway obstruction, hyper-responsiveness and pulmonary hyperinflation were similarly increased in both preterm cohorts compared to matched controls. Furthermore, current lung function was similarly related to neonatal respiratory disease in both birth-cohorts: FEV1 was reduced with respectively 18.6% and 18.7% of predicted in preterms dependent on supplemental oxygen at 36 weeks postmenstrual age. Lack of antenatal treatment with corticosteroids and prolonged neonatal oxygen treatment predicted similar significant airway obstruction in the two birth-cohorts.
Conclusion: Preterms born in different eras of neonatology had similar long-term decreases in lung function. Long periods of oxygen supplementation are still required to salvage immature infants, and airway obstruction may still be a common long-term outcome.