Obesity in Pregnancy: The Effect of Dietary Advice

Abstract

Plasma glucose and insulin concentrations, body weight, and skinfold thickness were measured at 16 and 36 wk of pregnancy and 5–7 days after delivery in 37 women with normal glucose tolerance. Nine thin women [less than 80% ideal body weight (IBW)], 10 normal women (90-110% IBW), and 10 obese women (more than 120% IBW) were allowed to eat according to appetite. Another eight obese women were advised to restrict their carbohydrate intake to between 150 and 180 g while maintaining the calorie content of their diet between 1800 and 2000 cal. The thin, normal, and obese women displayed a net weight increase between 16 wk and 5–7 days after delivery of 6.3, 2.8, and 4.9 kg, respectively. The dieted obese women, however, showed a mean weight loss of 2.3 kg. There was a strong association between the overall pregnancy weight gain and the change in skinfold measurements between 16 wk and delivery in the women studied. A significant decrease in glucose tolerance was observed in all four groups, although this was least in the dieted women and greatest in the thin. The mean basal and glucose-stimulated insulin concentrations of the two obese groups were found to be significantly higher at 16 wk than those of the normal women. In the thin, normal, and obese subjects the mean basal and glucose-stimulated insulin concentrations at 36 wk were double those observed at 16 wk of pregnancy. A much smaller increase in insulin concentrations occurred between 16 and 36 wk in the dieted obese group. It is concluded that obesity preceding pregnancy produces a stress on carbohydrate metabolism, which can be ameliorated if an isocaloric diet with mild carbohydrate restriction is advised. No adverse effect on neonatal outcome was observed.