A multivariate regression model for independent risk factors associated with ROP development is shown in Table 2. Birth weight (aOR 0.003; p = 0.002), Hb level (aOR 0.70; p = 0.006), presence of RDS (aOR 7.61; p = 0.011) and need for PRBC transfusion (aOR 4.26; p = 0.035) were independently associated with ROP development. This evidence concerns the gene GSTM1 and retinopathy of prematurity.