Purposes: To elaborate models for the estimation of fetal weight and longitudinal reference intervals of estimated fetal weight (EFW) using a sample of the Brazilian population.
Methods: Prospective observational study. Two groups of patients were evaluated: Group EFW (estimation of fetal weight): to elaborate (EFW-El) and validate (EFW-Val) a model for the prediction of fetal weight; Group LRI (longitudinal reference intervals): To elaborate (LRI-El) and validate (LRF-Val) conditional (longitudinal) percentiles of EFW.