A twin-paired study on the independent effect of birth weight on retinopathy of prematurity.

Purpose: To evaluate the effect of discrepancy between birth weight (BW) of twin preterm babies on retinopathy of prematurity (ROP) development.

Methods: Medical records of twins who were followed up for ROP between 2014 and 2023 were reviewed retrospectively. A total number of 254 twin babies with a gestational age (GA) of ≤ 34 weeks were included in the study. All patients were divided into 2 groups according to BW; the pairs with lower BW in Group 1 and their co-twins with higher BW in Group 2. Then, the discrepancy of ROP between groups was compared by within-pair analysis.

Results: The mean GA and BW was 32.08 ± 1.95 weeks and 1806.63 ± 441.52 g, respectively. Any stage ROP was detected in 109 (21.5%) twin pairs and ROP requiring treatment was found in 30 (5.9%) babies. There were no significant differences in ROP development, ROP stages and type of treatment between larger and smaller infants, in twin-paired analysis (p = 0.331, p = 0.511 and p = 0.655, respectively). Binary logistic regression analysis showed that the smaller GA and lower BW were associated with the risk of any stage ROP in both groups. However, there was no significant relationship between perinatal risk factors (GA and BW) and ROP stages or need for treatment in babies with ROP in both groups (p > 0.05).

Conclusion: Lower BW and smaller GA have a risk for any stage ROP in twin pairs. However, being the smaller baby is not the only predictor of ROP development in twin babies with the same GA but different BW.