At the univariate analysis (Table 2) GA (p = 0.008), BW (p = 0.007), PDA (p =0.002), IVH (p = 0.001), early and late onset sepsis (p = 0.001), BPD (p = 0.002) and EPO therapy (p < 0.001), showed a significant association with the occurrence of ROP. This evidence concerns the gene EPO and Patent ductus arteriosus.