Adult Respiratory Outcomes of Extreme Preterm Birth. A Regional Cohort Study

Abstract

Lifetime respiratory function after extremely preterm birth (gestational age≤28 wk or birth weight≤1,000 g) is unknown. To compare changes from 18-25 years of age in respiratory health, lung function, and airway responsiveness in young adults born extremely prematurely to that of term-born control subjects. Comprehensive lung function investigations and interviews were conducted in a population-based sample of 25-year-old subjects born extremely prematurely in western Norway in 1982-1985, and in matched term-born control subjects. Comparison was made to similar data collected at 18 years of age. At 25 years of age, 46/51 (90%) eligible subjects born extremely prematurely and 39/46 (85%) control subjects participated. z-Scores for FEV1, forced expiratory flow at 25-75% of vital capacity, and FEV1/FVC were significantly reduced in subjects born extremely prematurely by 1.02, 1.26, and 0.88, respectively, and airway resistance (kPa/L/s) was increased (0.23 versus 0.18). Residual volume to total lung capacity increased with severity of neonatal bronchopulmonary dysplasia. Responsiveness to methacholine (dose-response slope; 3.16 versus 0.85) and bronchial lability index (7.5 versus 4.8%) were increased in subjects born extremely prematurely. Lung function changes from 18 to 25 years and respiratory symptoms were similar in the prematurely born and term-born groups. Lung function in early adult life was in the normal range in the majority of subjects born extremely prematurely, but methacholine responsiveness was more pronounced than in term-born young adults, suggesting a need for ongoing pulmonary monitoring in this population.