This is an ambispective observational case-control study evaluating respiratory exacerbations in pediatric patients affected by bronchopulmonary dysplasia (BPD) compared with children without BPD. The study includes a retrospective cohort (January 2020 to September 2025) and a prospective cohort (from study approval to December 2030). Patients admitted to the Pediatric Emergency Department or Pediatric Unit for lower respiratory tract infections will be consecutively enrolled and managed according to standard clinical practice.