Twin and triplet discordance in retinopathy of prematurity: a call to integrate genomic, placental, and environmental determinants.

Background: Retinopathy of prematurity (ROP) is a major cause of preventable blindness in preterm infants, especially in multiple births such as twins and triplets. Although the incidence of ROP in these groups is well-documented, the discordance in disease severity among siblings has not been thoroughly investigated. This study aimed to quantify the discordance of ROP in twins and triplets and to identify associated predictive factors.

Methods: A cross-sectional study was conducted at the Poostchi ROP Clinic in southern Iran, involving 339 preterm infants from twin and triplet pregnancies undergoing screening for ROP. Data were collected on demographic, clinical, and ROP-specific variables, including gestational age (GA), birth weight (BW), duration of oxygen therapy, and ROP stage. Discordance was defined as a difference in ROP stage between siblings. Stepwise Poisson regression was employed to identify predictors of discordance.

Results: ROP discordance was observed in 88 neonates (26.0%), comprising 52 twins and 36 triplets. GA emerged as the only significant predictor of ROP severity (prevalence ratio = 0.90, 95% CI: 0.83-0.97, p = 0.012). No other variables, including BW, sex, or medical interventions, demonstrated significant associations. A post-hoc power analysis revealed limited statistical power for detecting subtle effects or rare events, indicating the necessity for larger studies.

Conclusion: ROP discordance was present in over one-quarter of neonates from multiple births, with GA as the primary influencing factor. The multifactorial nature of discordance highlights the need for larger, multicenter studies that incorporate genetic, placental, and prenatal data to optimize individualized neonatal care and prevent vision loss in this high-risk population.