Pregnancy and lactation are reproductive periods that require major energy and nutrient investment by the mother. Dietary perturbations over reproduction can impair offspring development and increase the risk of metabolic disease for the mother. However, how the intake of specific macronutrients, independent of total calorie intake, influence maternal reproductive investment and metabolic health remains poorly understood. To understand the role of protein, carbohydrate and fat intake in influencing these parameters we fed mice one of ten isocaloric diets that differed systematically in their macronutrient make-up. We allowed females to breed and observed striking effects of different macronutrients on fetal development, with protein intake having strong positive effects on offspring survival, accompanied by major shifts in the morphological structure of the placenta and placental lactogen production. However, maternal glucose tolerance was strongly impaired by high protein intake during pregnancy, with reproductive females more susceptible to the effects of these macronutrients than non-pregnant animals. During lactation, we also observed that offspring development was optimized by a different ratio of macronutrients compared to during pregnancy. These results highlight the importance of optimizing macronutrient intake during pregnancy to ensure optimal health for the mother and her offspring.