In our study, IL6 (rs2069832, rs1474347), EGFR (rs11506105, rs17336919) and MMP9 (rs3787268), CD44 (rs34986068, rs7639388, rs3215691), and SERPINE1 (rs2227692, rs2854236) SNPs were more common to non-BPD group, suggesting these SNPs are not risk factors of BPD (Supplementary Table 2). This evidence concerns the gene MMP9 and bronchopulmonary dysplasia.