Energy requirements during pregnancy and lactation.

OBJECTIVE To estimate the energy requirements of pregnant and lactating women consistent with optimal pregnancy outcome and adequate milk production. DESIGN Total energy cost of pregnancy was estimated using the factorial approach from pregnancy-induced increments in basal metabolic rate measured by respiratory calorimetry or from increments in total energy expenditure measured by the doubly labelled water method, plus energy deposition attributed to protein and fat accretion during pregnancy. SETTING Database on changes in basal metabolic rate and total energy expenditure during pregnancy, and increments in protein based on measurements of total body potassium, and fat derived from multi-compartment body composition models was compiled. Energy requirements during lactation were derived from rates of milk production, energy density of human milk, and energy mobilisation from tissues. SUBJECTS Healthy pregnant and lactating women. RESULTS The estimated total cost of pregnancy for women with a mean gestational weight gain of 12.0 kg, was 321 or 325 MJ, distributed as 375, 1200, 1950 kJ day(-1), for the first, second and third trimesters, respectively. For exclusive breastfeeding, the energy cost of lactation was 2.62 MJ day(-1) based on a mean milk production of 749 g day(-1), energy density of milk of 2.8 kJ g(-1), and energetic efficiency of 0.80. In well-nourished women, this may be subsidised by energy mobilisation from tissues on the order of 0.72 MJ day(-1), resulting in a net increment of 1.9 MJ day(-1) over non-pregnant, non-lactating energy requirements. CONCLUSIONS Recommendations for energy intake of pregnant and lactating women should be updated based on recently available data.