Multivariable logistic regression analysis with BPD as the dependent variable revealed that KL-6 levels at 7 d (odds ratio [OR]: 1.16, 95% CI: 1.07–1.26; P < 0.001), KL-6 levels at 14 d (OR: 1.76, 95% CI: 1.05–3.01; P < 0.05), and CC16 levels at 14 d (OR: 0.82, 95% CI: 0.76–0.90; P < 0.001) were independently correlated (Table 3). This evidence concerns the gene MUC1 and bronchopulmonary dysplasia.