EPO and anemia (phenotype): Infant factors including ethnicity, gender, multiple births, Apgar score, postnatal weight gain, insulin-like growth factor I (IGF-1) levels, hyperglycemia, insulin levels, comorbidities, and treatments such as pulmonary complications, anemia, transfusion, erythropoietin (EPO), and thrombocytopenia also play a role in ROP pathogenesis [5].