Published online by Cambridge University Press: 06 April 2009
The energy requirement of pregnancy reflects a problem which contains a great deal of uncertainty. To supply the theoretical energy needs for the increases in maternal and foetal tissues and to cover the elevated basal metabolic rate involves an amount equivalent to an extra 250–300 kcal/day on average, but in real-life situations there is seldom a rise in dietary energy of a comparable quantity. Data from co-ordinated longitudinal studies in four countries, together with results from other published papers, show energy intakes increasing by only 100–150 kcal/day, and only in the third trimester. Although it is difficult to demonstrate, the probability is that there are energy savings in reduced physical activity which compensate for the larger energy needs.