To determine the risk factors, especially maternal risk factors, associated with the development of retinopathy of prematurity (ROP) in premature babies.A matched case-control study involving premature patients was undertaken retrospectively. The case group consisted of premature babies with the subsequent development of ROP. The control group consisted of gestational age-matched and sex-matched premature babies that did not develop ROP during the follow-up period. Risk factors involving patient demographics and maternal characteristics were compared between the case and control groups.A total of 144 patients were included in this study (72 patients in the case group and 72 patients in the control group). Among the 66 possible risk factors compared, only birth weight and maternal age were found to be significant risk factors. Birth weight was significantly lower in the case group (1,248.7 +/- 257.8 g vs. 1,335.5 +/- 297.2 g, P = 0.01), and maternal age was significantly older in the case group compared with that in the control group (31.2 +/- 5.1 years vs. 28.2 +/- 5.3 years, P 30 years.Older maternal age is a newly identified risk factor for the development of ROP in premature babies.