Obstructive lung disease is an increasing global health problem of pandemic proportions, with COPD alone affecting >10% of the population. Smoking is the main and most well studies risk factor for developing COPD. However, chronic airway obstruction also in never-smoking populations has recently been recognized as an increasing health problem. Prematurely born children, particularly survivors of bronchopulmonary dysplasia (BPD), defined as the need for oxygen therapy up to the 28th day of life for children born prior to gestational week 32, have an increased incidence of both airway obstruction and hyper-reactivity, both representing major risk factors for developing COPD, or asthma, later in life. The purpose of this study is to perform in-depth clinical and molecular characterizations of of the lungs of survivors of BPD as they enter adulthood, and compare these profiles to relevant control groups (individuals with mild asthma, healthy prematurely born, and healthy individuals born at full term). Specifically, alterations at the epigenetic, mRNA, microRNA, protein and metabolite level as well as associated molecular pathways critical in the pathological mechanisms of obstructive lung disease related to premature birth and BPD will be identified.