The lack of gestational weight gain (GWG) recommendations for low- and middle-income countries is a significant concern. To identify the ranges on the Brazilian GWG charts associated with lowest risks of selected adverse maternal and infant outcomes. Data from 3 large Brazilian datasets were used. Pregnant individuals aged ≥18, without hypertensive disorders or gestational diabetes were included. Total GWG was standardized to gestational age-specific z-scores according to Brazilian GWG charts. A composite infant outcome was defined as the occurrence of any of small-for-gestationa lage (SGA), large-forgestationa lage (LGA), or preterm birth. In a separate sample, postpartum weight retention (PPWR) was measured at 6 and/or 12 mo postpartum. Multiple logistic and Poisson regressions were performed with GWG z-scores as the exposure and individual and composite outcomes. GWG ranges associated with the lowest risk of the composite infant outcome were identified using noninferiority margins. For the neonatal outcomes, 9500 individuals were included in the sample. For PPWR, 2602 and 7859 individuals were included at 6 and 12 mo postpartum, respectively. Overall, 7.5% of the neonates were SGA, 17.6% LGA, and 10.5% were preterm. Higher GWG z-scores were positively associated with LGA birth, whereas lower z-scores were positively associated with SGA births. The risk of the selected adverse neonatal outcomes were lowest (within 10% of lowest observed risk) when individuals with underweight, normal weight, overweight, or obesity gained between 8.8–12.6; 8.7–12.4; 7.0–8.9; and 5.0–7.2 kg, respectively. These gains correspond to probabilities of PPWR ≥5 kg at 12 mo of 30% for individuals with under and normal weight, and <20% for overweight and obesity. This study provided evidence to inform new GWG recommendations in Brazil.