Table 4.

The rate of development of ROP and significant risk factors in some studies

Study	Sample size	Rate of ROP	Risk factors
Liu et al ${}^{[}{}^{12]}$	472	12.7%	Gestational age, birth weight, preeclampsia, and maternal oxygen supplement before or at the time of delivery
Port et al ${}^{[}{}^{17]}$	582	29%	Univariate analysis: birth weight, gestational age, patent ductus arteriosus, sepsis, intraventricular hemorrhage (IVH), lung disease, days of hyperglycemia, and prescription of postnatal steroids Multivariate analysis: gestational age, days of hyperglycemia, and days of mechanical ventilation
Bossi et al ${}^{[}{}^{18]}$	318	37.1%	Gestational age $\le$ 32 weeks, birth weight $\le$ 1250 g, oxygen therapy, and sepsis
Kim et al${}^{[}$ ${}^{19]}$	211	42%	Poor weight gain during the first two weeks
This study	1,990	28.9%	Univariate analysis: gestational age, birth weight, transfusion, ARDS, oxygen therapy, sepsis, intubation, and intraventricular hemorrhage (IVH) Multivariate analysis: gestational age, birth weight, and history of transfusion
ARDS, acute respiratory distress syndrome; ROP, retinopathy of prematurity