Lactation is one of the most nutritionally demanding periods of a woman’s life, when her nutritional requirements increase beyond both prepregnant and pregnant levels in order to support newborn and infant growth and development, and to maintain her own metabolic needs. Infants double their weight in the first 4 to 6 months postpartum, and the breast milk secreted in the first 4 months represents an amount of energy similar to the total energy cost of pregnancy [1]. Although the energy and nutrients stored during pregnancy are available to support milk production, there are undoubted increases in requirements for a broad range of nutrients during lactation. Most of these recommended intakes are based on our knowledge of the amount of milk produced during lactation, its energy and nutrient content, and the amount of maternal energy and nutrient reserves. Despite the increased nutrient demands of lactation, women are remarkably resilient in their ability to produce breast milk of sufficient quantity and quality to support the growth of their infant, even when the mother is deprived of nutrients herself. During lactation, the mammary gland exhibits metabolic priority for nutrients, often at the expense of maternal reserves. 54Milk production may, therefore, have an impact on maternal body composition and nutritional status, and could impact negatively on any subsequent pregnancy, particularly if the interval between pregnancies is short. Pregnancies with short “recuperative intervals” (defined as the amount of time that the woman was not lactating prior to the next conception) may be particularly vulnerable to nutrient depletion. Yet reviews of the evidence, while highlighting weaknesses in the available studies, have found no clear evidence of a link between interpregnancy or recuperative interval and maternal anthropometric status, possibly due, in part, to changes in the hormonal regulation of nutrient partitioning between the mother and the fetus when a mother is malnourished [2,3].