This study was undertaken at the request of the Maternal and Child Health Program (Title V, Social Security Act) of the Health Resources and Services Administration, U.S. Department of Health and Human Services. In response to that request, the Food and Nutrition Board's Committee on Nutritional Status During Pregnancy and Lactation and its Subcommittee on Nutrition During Lactation were asked to evaluate current scientific evidence and formulate recommendations pertaining to the nutritional needs of lactating women, giving special attention to the needs of lactating adolescents; women over age 35; and women of black, Hispanic, or Southeast Asian origin. Part of this task included consideration of the effects of maternal dietary intake and nutritional status on the volume and composition of human milk, the appropriateness of various anthropometric methods for assessing nutritional status during lactation, and the effects of lactation both on maternal and infant health and on the nutritional status of both the mother and the infant.

The study was limited to consideration of healthy U.S. women and their healthy, full-term infants. The Subcommittee on Nutrition During Lactation conducted an extensive literature review, consulted with a variety of experts, and met as a group seven times to discuss the data and draw conclusions from them. The Committee on Nutritional Status During Pregnancy and Lactation (the advisory committee) reviewed and commented on the work of the subcommittee and helped establish appropriate linkages between this report and the reports on weight gain and nutrient supplements during pregnancy contained in Nutrition During Pregnancy—a report prepared by two other subcommittees of this advisory committee (IOM, 1990). Compared with earlier reports from the National Research Council, Nutrition During Pregnancy recommended a higher range of weight gain (11.5 to 16 kg, or 25 to 35 lb, for women of normal prepregnancy weight for height). In addition, it advised routine low-dose iron supplementation during pregnancy, but supplements of other vitamins or minerals were recommended only under special circumstances.

In examining the nutritional needs of lactating women, priority was given to energy and to those nutrients believed to be consumed in amounts lower than Recommended Dietary Allowances (RDAs) by many women in the United States. These nutrients include calcium, magnesium, iron, zinc, folate, and vitamin B₆. Careful attention was given to the effects of lactation on various indicators of nutritional status, such as measurements of levels of biochemical compounds; functions related to specific nutrients; nutrient levels in specific body compartments; and height, weight, or other indicators of body size or