Glycemic control throughout pregnancy and fetal growth in insulin-dependent diabetes

To determine the time of growth acceleration in fetuses of insulin-dependent diabetic women who are large for gestational age (LGA) at birth and the relationship between growth acceleration and diabetic control throughout pregnancy.

We studied a consecutive sample of 76 women with insulin-dependent diabetes divided by those who delivered LGA or normally grown infants. Fetal abdominal circumference (AC) was measured ultrasonically at regular intervals between 20 and 34 weeks' gestation. Diabetic control was assessed by regular measurement of glycosylated hemoglobin and capillary blood glucose levels.

A significant difference in fetal AC between groups developed between 20 and 24 weeks' gestation, and the LGA group continued to have accelerated fetal growth. Between 18 and 24 weeks glycosylated hemoglobin and capillary blood glucose concentrations were significantly higher in women who delivered LGA infants. After 28 weeks, blood glucose concentrations and glycosylated hemoglobin did not differ significantly between groups. There was a nonsignificant trend toward more vaginal deliveries in the normal group (45% versus 32%).

In insulin-dependent diabetic pregnancy, although actual growth acceleration occurred from about 20 weeks' gestation, growth potential of fetuses appeared to be determined by prevailing maternal glucose concentrations before then. Excessive growth continued despite subsequent satisfactory glucose control. If strict blood glucose control is maintained during first and second trimesters, it might reduce the incidence of LGA infants.