Introduction: There is no consensus on the growth curve to be used to assess fetalgrowth. Objectives: To validate customized curves and study their performancein the detection of neonates with intrauterine growth restriction (IUGR), as wellas their diagnostic accuracy. Methods: Initially, customized curves were designedwith 2,792 singleton fetuses from low-risk pregnancies; the optimal weight at 40weeks = 1,496.202 + (64.379 x fetal sex) + (831.362 x maternal length) + (9.567 xpregestational weight) was calculated and combined with a standard proportionalityfunction to adjust the weights according to gestational age. Subsequently, itsperformance was evaluated by applying it in a retrospective cohort of neonates aged24–40 weeks born between 2018-2022 in a tertiary hospital in Lima-Peru. Twins andcongenital anomalies were excluded. Results: A total of 6,598 neonates were studied.Customiz...