['To investigate whether postnatal weight at first detection of retinopathy of prematurity (ROP) can predict preterm infants who will develop severe ROP warranting treatment.', 'This modern, population-based cohort included 147 infants born at gestational age (GA) <32\u2005weeks in the Gothenburg region during 2011-2012 and screened for ROP at Sahlgrenska University hospital. GA, birth weight (BW), and weekly postnatal weight from birth until postmenstrual age (PMA) 40\u2005weeks data were retrospectively retrieved. Birth weight SD scores (BWSDS) were calculated. ROP data, including first detected ROP stage, maximal ROP stage, ROP treatment, and PMA at first detected sign of ROP were also retrieved. Weight SDS (WSDS) at first ROP detection was calculated.', 'Stepwise multivariate logistic regression analysis revealed that the best fit-model of risk factors for developing severe ROP warranting treatment included; GA (OR=0.28, CI 95% 0.12 to 0.66, p<0.01) and WSDS at first ROP detection (OR=0.22, CI 95% 0.05 to 0.89, p<0.05).'] Does weight at first detection of retinopathy of prematurity predict disease severity?