Nutrient requirements during the life stages of pregnancy and lactation are increased relative to women who are not pregnant or lactating. The energy requirements increase by an estimated 300 kcal/day during the second and third trimesters of pregnancy and by 500 kcal/day during lactation. In practice, most women require only approximately 200 additional kcal/day due to reduced levels of physical activity during pregnancy and to increased lipolysis of fat stores during breast-feeding. Relative to the increased energy requirement, the requirements for many micronutrients (vitamins and nutritionally essential minerals) are even higher during pregnancy and lactation