Fat mass accumulation during pregnancy in women with gestational diabetes mellitus

Objective The objective of this study was to assess fat and fat-free mass d eposition during gestation in normal women and in women with gestational di abetes mellitus. Methods Twenty-two pregnant women were followed prospectively from 19 gesta tional weeks until term. Eight of these women were diagnosed with gestation al diabetes mellitus during late gestation. At the initial visit, pregestat ional weight, height and medical history were obtained. At all visits, mate rnal weight was measured on a balance beam scale and body composition was d etermined using a bioimpedance meter. Reactance and resistance values were used to calculate total body water, lean body mass and body fat. The women were followed until delivery, with a mean of five visits per patient. Results No significant difference was found in either pregestational weight (71.8 +/- 12.7 kg for controls versus 71.1 +/- 10.0 kg for women with gest ational diabetes mellitus) or body mass index (26.5 +/- 5.2kg/m(2) for cont rols and 29.3 +/- 2.0 kg/m(2) for gestational diabetes women). By 20 weeks' gestation, the women with gestational diabetes were heavier than controls (84.7 +/- 14.4 kg versus 74.5 +/- 16.4 kg, respectively) but no significant difference was found in percentage body fat (37.5 +/- 7.7% for controls an d 40.1 +/- 5.2% for gestational diabetes women) between the two groups. Dur ing the third trimester of pregnancy, the diabetic women increased their pe rcentage fat mass at a greater rate than normal women (0.56 +/- 0.23 versus 0.35 +/- 0.13% per week; p < 0.017) while their weight gain during this pe riod was similar (7.1 +/- 4.4 versus 7.3 +/- 2.8 kg; NS). Conclusion Maternal fat mass accumulation during the third trimester of pre gnancy in women with gestational diabetes exceeded that found in normal hea lthy controls. This accumulation could be related to the underlying conditi on (i.e. gestational diabetes) or alternatively, could be associated with t he development of gestational diabetes by augmenting the physiological insu lin resistance of pregnancy.