It has long been recognized that weight gain during pregnancy is one of the most important maternal factors predictive of infant birth weight.1 Maternal nutrition and weight gain during pregnancy are becoming increasingly important foci as we debate means of reducing the high incidence of low birth weight and neonatal mortality among children born in the United States. Recently, the Bureau of Maternal and Child Health and Resources Development of the US Department of Health and Human Services requested that the National Academy of Sciences undertake a study of maternal nutrition during pregnancy. The Committee on Nutritional Status During Pregnancy and Lactation was formed by the Food and Nutrition Board, Institute of Medicine. The portions of the Committee's report referred to in this piece are contained in the volume, Nutrition During Pregnancy,1 and were prepared by the Subcommittee on Nutritional Status and Weight Gain During Pregnancy. This volume