Prenatal risk factors for severe retinopathy of prematurity among very preterm infants of the Australian and New Zealand Neonatal Network

Objective. To identify prenatal and perinatal risk factors for clinically severe (stage 3 or 4) retinopathy of prematurity (ROP). Methods. Data were collected prospectively as part of the ongoing Australian and New Zealand Neonatal Network audit of high-risk infants (birth weight of <1500 g or gestational age [GA] of <32 weeks) admitted to a level III neonatal unit in Australia or New Zealand. Prenatal and perinatal factors to 1 minute of age were examined for the subset of infants with GA of <29 weeks who survived to 36 weeks' postmenstrual age and were examined for ROP (n = 2105). The factors significantly associated with stage 3 or 4 ROP were entered into a multivariate logistic regression model. Results. Two-hundred three infants (9.6%) had stage 3 or more ROP. Prematurity was the dominant risk factor, with infants with GA of <25 weeks having 20 times greater odds of severe ROP than infants with GA of 28 weeks. Birth weight for GA also had a "dose-response" effect; the more growth-restricted infants had greater risk, with infants below the 3rd percentile of weight for GA having 4 times greater odds of severe ROP than those between the 25th and 75th percentiles. Male gender was also a significant risk factor (odds ratio: 1.73; 95% confidence interval: 1.25-2.40). Conclusions. These data, for a large, essentially population-based cohort, suggest that factors related to the degree of immaturity, intrauterine growth restriction, and male gender contribute to severe ROP.