Patients with bronchopulmonary dysplasia (BPD) have shown clinical improvement after secundum atrial septal defect (ASD) closure. We sought to determine if this post‐ASD closure improvement is secondary to the expected course in BPD patients or related to the closure itself. A novel BPD‐ASD score was created to assess patients' clinical status (higher score = worse disease) and applied to 10 BPD‐ASD inpatients weighing ≤ 10 kg who underwent ASD closure. The score and its subcomponents were retrospectively calculated serially ranging from 8 weeks pre‐ to 8 weeks post‐intervention, and pre‐ and post‐intervention score slopes were created. These slopes were compared using mixed regression modeling with an interaction term. There was a significant difference in pre‐ versus post‐intervention slope with the most score drop the first week post‐intervention (−2.1 + /− 0.8, p = 0.014). The mean score also dropped through weeks 2 (slope −0.8 + /− 0.8, p = 0.013) and 4 (slope −1.0 + /− 0.5, p = 0.001) post‐intervention. There was a significant difference in pre‐ and post‐intervention slopes for diuretics (p = 0.018) and the combined score of respiratory support, FiO2 need, and respiratory symptoms (p = 0.018). This study demonstrated significant improvement in BPD‐ASD score, diuretic need, and respiratory status after ASD closure in BPD‐ASD patients ≤ 10 kg that was outside of the natural course of BPD. Our study was limited by its small, single‐center, retrospective nature. Future studies should be performed in a larger multicenter population to both validate the scoring system and compare to non‐intervention infants.