AIM: To suggest a novel retinopathy of prematurity (ROP) screening model in developing countries incorporating postnatal weight gain ratios (PWGR) to traditional parameters to maintain sensitivity and improve specificity in detecting ROP. METHODS: Analysis of weekly PWGR of infants from one tertiary referral center during six months to determine the age at which the PWGR with the highest predictability for ROP development which was referred to as the postnatal net weight gain ratio (NWGR). NWGR was added to conventional criteria to describe a new model (The Alex-ROP model). RESULTS: Of 560 infants were included. NWGR 28d after birth was the most predictive factor for the development of ROP. A new model Alex-ROP recommending screening infants with gestational age (GA) ≤33wk or birth weight ≤1500 g and NWGR at 28d after birth <0.3 was suggested. A second screening model referred to as High-grade Alex-ROP (Hg Alex-ROP) model to detect worse grade ROP (Both type 1 and type 2) recommending a cutoff point of NWGR <0.15 between birth and 28th day. CONCLUSION: Both Alex-ROP and Hg Alex-ROP models are easy to apply to improve the specificity of ROP screening in developing countries while maintaining high sensitivity.