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

Rationale Lifetime respiratory function after extremely preterm birth (gestational age ≤28 wk or birth weight ≤1,000 g) is unknown. Objectives 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. Methods 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. Measurements and Main Results 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. Conclusions 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.