Anemia of Prematurity: Risk Factor for Retinopathy of Prematurity in Later Preterm and Heavier Birth Weight Neonates

To evaluate anemia of prematurity (AOP) as an independent risk factor for retinopathy of prematurity (ROP) across gestational-age and birth-weight strata, including later preterm and higher birth weight infants traditionally considered lower risk.

We conducted a retrospective population-based study using the National Inpatient Sample from 2016-2021. Preterm neonates (≤36 weeks' gestational age) were identified and stratified by gestational age and birth weight. Multivariable logistic regression analyses were restricted to urban teaching hospitals and adjusted for demographic factors and markers of neonatal illness severity and supraphysiologic oxygen exposure, including red blood cell transfusions, respiratory distress syndrome, bronchopulmonary dysplasia, mechanical ventilation, and intraventricular hemorrhage.

Among 293,910 preterm neonates, ROP was identified in 2.8%. Anemia of prematurity was significantly more prevalent among infants with ROP than those without (82.4% vs 11.7%, p<0.001). Across gestational-age-stratified multivariable models, AOP was independently associated with increased odds of ROP in all strata, with adjusted odds ratios ranging from 2.66 to 9.63 (all p<0.01). The strongest associations were observed among later preterm infants (32-36 weeks) and higher birth weight infants (≥1500 g).

Anemia of prematurity is independently associated with retinopathy of prematurity across the spectrum of prematurity, including infants traditionally considered lower risk. Incorporating anemia of prematurity into ROP risk stratification may help identify vulnerable infants who warrant closer ophthalmologic surveillance beyond current screening criteria.