Some physiological adjustments relating to nutrition in pregnancy.

Information from human and animal studies clearly indicates that a number of adjustments in protein, fat, iron and calcium metabolism occur during pregnancy. Recognition of these adjustments has led to a reappraisal of nutrient requirements during pregnancy. The existence of significant protein storage during pregnancy is called into question; in contrast, the evidence suggests that the major storage component is fat, perhaps in anticipation of the energy costs of lactation. In women who will not lactate, this storage is of no benefit and is an etiologic factor in obesity. From a consideration of iron metabolism in pregnancy, it is concluded that it is better to prevent iron depletion in non-pregnant women, especially that associated with excessive menstrual loss, than to administer iron therapy to pregnant women.