The influence of obesity and gestational diabetes mellitus on accretion and the distribution of adipose tissue in pregnancy.

Objective: The purpose of this study was to evaluate the effect of pregravid obesity and gestational diabetes mellitus (GDM) on the longitudinal accretion and distribution of adipose tissue in pregnancy.

Study Design: Women with normal glucose tolerance and GDM were evaluated before conception, early (12-14 weeks) and late (33-36 weeks) in gestation. Fat mass, lean body mass, and percent body fat were assessed longitudinally with hydrodensitometry. Serial biceps, triceps, subscapular, iliac, costal, mid thigh, and lower thigh skinfold measurements quantified the changes in fat mass distribution. Pregravid obesity was defined as >25% body fat.

Results: Subjects included 19 patients with GDM (5 lean women, 14 obese women), and 33 patients with normal glucose tolerance (controls; 12 lean women, 21 obese women). GDM and control subjects were similar in pregravid percent body fat (29.6% vs 27.9%, P=.47) and fat mass (20.8 kg vs 18.2 kg, P=.37). Values for subjects with GDM and controls were also similar in terms of percent body fat, fat mass, and weight gained (change in percent body fat, -0.7% vs 1.9% [P=.07]; change in fat mass, 3.8 kg vs 5.0 kg [P=.08]; change in weight, 12.0 kg vs 13.2 kg [P=.35]). Lean subjects gained more percent body fat compared with obese subjects (change in percent body fat, 3.3% vs 0.1% [P=.004]) but gained similar amounts of fat mass (change in fat mass, 4.7 kg vs 4.2 kg [P=.58]), lean body mass (7.6 kg vs 8.8 kg [P=.18]), and weight (change in weight, 12.3kg vs 13.0 kg [P=.61]) The distribution of adipose tissue that was accumulated as estimated with skinfold measurements was similar between patients with GDM and glucose tolerance (P>.05 for all changes in skinfolds), but significantly different between lean and obese patients (P<.05 for all changes in skinfolds). Lean women gained a predominance of adipose tissue peripherally over that in obese women.

Conclusion: Lean women accrue significantly more fat mass than obese women, regardless of glucose tolerance. Pregestational obesity rather than GDM influences the distribution of adipose accretion.