The goal of this observational study is to learn about the correlation between respiratory system reactance, as assessed by respiratory oscillometry, and respiratory outcomes in preterm infants born before 32 weeks of gestation. The main question it aims to answer is if the reactance z-score at 7 postnatal days adds to relevant clinical factors in the prediction of bronchopulmonary dysplasia. Participants will receive respiratory oscillometry measurements at 7 ± 2 postnatal days.