Low social status is associated J with depressed fetal growth, high perinatal mortality, and disadvantageous mental development. Suboptimal calorie and protein nutrition during pregnancy is a likely causal link in this chain: it is coherent with the relationship of low birth weight with famine conditions, with low maternal weight and weight gain, with the economic constraints of poverty, and with reported gradients of dietary intake of protein by social status during pregnancy. 1-3 It is possible that intervention to improve nutrition during the last few months of pregnancy, when most women receive prenatal care and are thus accessible to treatment, may be of considerable benefit. 4 We are testing this hypothesis in a randomized, double-blind, controlled clinical trial of protein and calorie supplementation during pregnancy in a poor, urban, black, North American population. 5,6 The randomized, controlled study design was necessary for a number of reasons, such as covariation of