Chronic Lung Disease of Prematurity

The purpose of this study is to determine if an investigational drug can prevent Bronchopulmonary Dysplasia, reducing the burden of chronic lung disease in extremely premature infants, as compared to extremely premature infants receiving standard neonatal care alone.

This observational study aims to compare responses to different, commonly used inhaled bronchodilators in children born preterm with bronchial obstruction at spirometry. All children were diagnosed with Chronic Lung Disease of Immaturity (CLDI). The main questions are: * Is any inhaled bronchodilator or their combination generally superior in children with CLDI when assessing the reversibility of bronchial obstruction? * Is there an individual difference in the effect of betamimetic, anticholinergic or their combination between children with CLDI? Participants will: * Come to our clinic in a stable state without acute infection and they will be randomly assigned to the first inhaled bronchodilator. * They will then perform a spirometry test before and after the inhalation of the drug. * This visit will repeat 3 times, each with a different bronchodilator (beta2agonist, anticholinergic and their combination).