Changes in total body composition during normal and diabetic pregnancy. Relation to oxygen consumption

Serial changes in body composition during pregnancy have been measured in 5 normal and 2 diabetic women on controlled diets to compare with simultaneous measurements of oxygen consumption (V-O2). Total body water (TBW) was measured by D2O dilution, total body fat (TBF) calculated as 100-%TBW/0.732 and body cell mass (BCM) derived from total body 40K count by Moore's formula, BCM equals K-e times 8.33. Two normal subjects in caloric equilibrium lost 1.2 kg TBF, gained 5.5 kg TBW and 4.1 kg BCM. Two obese subjects in negative caloric balance lost 4.7 kg TBF, gained 7.3 kg TBW and 4.3 kg BCM. One subject on ad lib diet gained 7.7 kg TBF, 0.6 kg TBW, and 2.6 kg BCM. She continued to gain fat postpartum. Two diabetic subjects gained fat up to 28 weeks, lost it thereafter, and showed no net gain in BCM. Basal V-O2 correlated with BCM, while 24-hour resting V-O2 related to total body weight. It is concluded that fat storage in human pregnancy depends on food intake, as in the nonpregnant. BCM accumulation is independent of food intake, except protein, and depends on normal physiologic adjustments of pregnancy, which are upset by insulin lack in diabetes. The extra basal energy needs of gestation are determined by BCM acquisition, not total body weight.