Perinatal growth characteristics and associated risk of developing threshold retinopathy of prematurity

Purpose: To document perinatal growth characteristics in infants who developed threshold retinopathy of prematurity (ROP) in an attempt to describe prenatal and postnatal growth-related risk factors for threshold ROP. Methods: To document birth weight as well as absolute and relative weight gain (g/d and g/kg/d) in the first 6 weeks of life in infants who developed threshold ROP and who were admitted to a single tertiary neonatal intensive care unit between 1996 and 2000. These data were compared (case-control approach) with infants of the same gestational age (GA) who did not developed threshold ROP. Results: Small for gestational age (SGA; ie, weight <10th percentile for a given GA) and growth restriction (<25th percentile for a given GA) are risk factors for threshold ROP (relative risk = 3.7 and 4.5, respectively). Absolute weight gain (g/d) is also associated with an increased risk of developing threshold ROP (P < .05). In contrast, relative weight gain (g/kg/d) is not significantly different between threshold ROP infants and GA-matched controls. Conclusions: SGA and a birth weight below the 25(th) percentile are risk factors for threshold ROP. Postnatal weight and absolute weight gain (g and g/d, respectively) in the first 6 weeks of life are statistically significant but of less clinical relevance because smaller infants at birth stay relatively smaller during the first 6 weeks of life. Even with normal (ie, same weight as control infants) postnatal relative weight gain (g/kg/d), growth retarded or restricted infants at birth still have an increased risk of developing threshold ROP.