Trajectories of Pulmonary Function and Dysanapsis after Premature Birth

Background/Objectives Preterm survivors, with or without bronchopulmonary dysplasia (BPD) have decreased and progressive lung function decline. As neonatal care has improved survival, limited studies have compared lung function trajectories across birth epochs. Methods Retrospective study of subjects born <33 weeks who completed ≥1 pulmonary function test (PFT). BPD was classified per 2019 NICHD criteria. We analyzed spirometry values and Dysanapsis Ratio (DR). Birth epochs included Epoch A(<2000), B (2000-2009), and C(2010-2019). Results We analyzed 2,216 PFTs from 707 subjects; 319 (45.1%) had BPD. Pulmonary function decreased with increasing BPD severity. FEV1 decreased monotonically, from 92.0%(80.1-102.0) in preterm without BPD to 73.1%(57.7-84.9) in Grade 3, with consistent decreases in FVC (99.0%(87.0-110.0) to 85.2%(71.5-93.4). FEV₁/FVC remained largely constant, with a small decrease in Grade 3. Due to divergence in FEV1 and FVC trend with increasing age, FEV1/FVC yearly decline slope tripled in more recent epochs in subjects with BPD (Epoch A:-0.4%/yr(-0.8 to 0.05), B:-0.8%/yr(-1.1 to -0.5),, C:-1.4%/yr(-1.8 to -0.9). Similarly, DR decreased with age, with steeper decline in more recent epochs (Epoch A:-0.01/yr(-0.02 to -0.0004), B:-0.02/yr(-0.03 to -0.01), C:-0.04/yr(-0.05 to -0.03). Similar declines were noted for FEV1/FVC and DR in children without BPD. Conclusion In preterm survivors, lung function declined with increasing BPD severity and age. Lung function was reduced and declined in preterm children without BPD. Recent birth epochs exhibited faster decline in FEV1/FVC and worsening DR, indicating evolving airway-parenchymal growth mismatch despite advances in neonatal care, highlighting the need for longitudinal follow-up and targeted interventions to improve long-term outcomes.