The relationship between maternal body composition and fetal development is unclear. The objective of this study was to determine whether maternal body composition determines fetal growth in women with low, normal, and high energy intakes. Two hundred pregnant women were recruited from the Instituto Fernandes Figueira, Rio de Janeiro, Brazil. Dietary intake was assessed using a food frequency questionnaire validated for Brazilian adults and body composition was estimated using bioimpedance analysis. Fetal growth was assessed using serial ultrasound measure and infants underwent anthropometric measurements at birth. Multiple linear regression analyses were used to determine the association between fetal growth and birth weight with percent fat mass (%FM) and percent fat‐free mass (%FFM), controlling for infant gender, maternal serum glucose, and BMI. %FM was positively associated with birth weight adjusted for gestational age (BWTadj), estimated fetal weight change (ΔEFW), and change in fetal length (ΔFL), yet %FFM was negatively associated. When stratified by energy intake, %FM was a significant predictor of BWTadj in women with normal energy intake, but a significant predictor of ΔEFW and ΔFL in women with low energy intake. FM may be used as a reliable indicator of maternal nutritional status for individual recommendations on weight gain during pregnancy. This study was funded by the American Egg Board.