Recurrent risk
4.Methods Potential related risk factors of ROP, such as age, sex, birth weight, FiO 2, duration of inspiring ox ygen, hyaline membrane dzsease (HMD), Apgar score, intracranial hemorrhage(ICH) , recurrent apnea, broncho pulmonary dysplasia (BPD), patent ductus arteriosus ( PDA) were studied prospectively by univariate analysis and Logistic regression a nalysis in 135 preterm infants.

