Understanding the effects of balanced energy and protein (BEP) supplements on gestational weight gain and how the effects differ depending on maternal characteristics and the nutritional composition of the supplements will inform the implementation of prenatal BEP interventions. This study concluded that prenatal BEP supplements are effective in increasing gestational weight gain and reducing the risk of inadequate weight gain during pregnancy. BEP supplementation targeted toward pregnant women with undernutrition may be a promising approach to delivering the supplements.