Children Born Preterm at the Turn of the Millennium Had Better Lung Function Than Children Born Similarly Preterm in the Early 1990s

Abstract

Objective Compare respiratory health in children born extremely preterm (EP) or with extremely low birthweight (ELBW) nearly one decade apart, hypothesizing that better perinatal management has led to better outcome. Design Fifty-seven (93%) of 61 eligible 11-year old children born in Western Norway in 1999-2000 with gestational age (GA) <28 weeks or birthweight <1000 gram (EP1999-2000) and matched term-controls were assessed with comprehensive lung function tests and standardized questionnaires. Outcome was compared with data obtained at 10 years of age from all (n = 35) subjects born at GA <29 weeks or birthweight <1001 gram within a part of the same region in 1991-92 (EP1991-1992) and their matched term-controls. Results EP1999-2000 had significantly reduced forced expiratory flow in 1 second (FEV1), FEV1 to forced vital capacity (FEV1/FVC) and forced expiratory flow between 25-75% of FVC (FEF25-75), with z-scores respectively -0.34, -0.50 and -0.61 below those of the term-control group, and more bronchial hyperresponsiveness to methacholine (dose-response-slope 13.2 vs. 3.5; p<0.001), whereas other outcomes did not differ. Low birthweight z-scores, but not neonatal bronchopulmonary dysplasia (BPD) or low GA, predicted poor outcome. For children with neonatal BPD, important lung-function variables were better in EP1999-2000 compared to EP1991-1992. In regression models, improvements were related to more use of antenatal corticosteroids and surfactant treatment in the EP1999-2000. Conclusions Small airway obstruction and bronchial hyperresponsiveness were still present in children born preterm in 1999-2000, but outcome was better than for children born similarly preterm in 1991-92, particularly after neonatal BPD. The findings suggest that better neonatal management not only improves survival, but also long-term pulmonary outcome.