Supplementary Material for: Association of intrauterine growth with retinopathy of prematurity risk in very preterm infants: a multicenter cohort study

Introduction: The impact of intrauterine growth status as measured by BW percentiles on retinopathy of prematurity (ROP) pathogenesis remains inadequately characterized. The objectives of the study was to establish BW percentile-specific risk gradients for ROP development. Methods: A multicenter cohort study was conducted with data were collected from Chinese Neonatal Network between January, 2019 and December, 2021. The exposure was GA- and sex-specific BW percentile. The primary outcome was incidence of ROP. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated, adjusted for potential confounders, and stratified by GA, infant sex, maternal hypertension, singleton/multiple birth. Results: Totally 17 882 preterm infants were enrolled, BW was 1300.0 (1100.0-1500.0) g and GA was 29.9 (28.6-31.0) weeks. The incidence was 27% for any stage ROP and 3.7% for severe ROP (stage 3 or above). Each decrease of BW percentile by 10% was associated with 15% increase of odds for either any stage ROP (aOR 0.85 [95% CI 0.83-0.86]) or severe ROP (aOR 0.85 [95% CI 0.82-0.89]). The optimal discriminative BW percentile on ROC curve was 26% for predicting any stage ROP and 19% for predicting severe ROP. Lower BW percentile under these cut-offs were associated with elevated odds of any stage ROP (aOR 2.20 [95% CI 1.97-2.47] and severe ROP (aOR 2.91 [95% CI 2.22-3.80]). Conclusions: ROP incidence was negatively associated with BW percentile. Each 10% decreased BW percentile was associated with 15% increased odds of any stage ROP and severe ROP.