Glucose tolerance and excessively large babies in nondiabetic mothers

Postpartum glycated hemoglobin A1c and glucose tolerance test in mothers of large babies

An attempt to study macrosomia and carbohydrate metabolism was made by determination of glycated hemoglobin A1c and by the oral glucose tolerance test (OGTT) in early puerperium. We studied 76 women who gave birth to large babies greater than or equal to 4.5 kg, 74 women whose babies were 3-4 kg as controls, and 36 type II diabetics. The median of HbA1c concentration in the diabetics (8.06%) was significantly higher than in the controls (6.49%), and the large babies' mothers (6.48%), P less than 0.001. No significant difference was found between HbA1c or glucose intolerance in mothers of large babies and mothers with average size babies. HbA1c showed an association with glucose levels in the diabetics and controls, P less than 0.001, but not in the large baby group. Mothers of large babies were as old and obese as the diabetics. We speculate that the relationship of postpartum GTT, HbA1c and gestational diabetes is unwarranted.

The relative contribution of different maternal factors in large-for-gestational-age pregnancies

Relative and attributable risks were calculated to assess the potency of different maternal factors associated with large-for-gestational age (LGA) babies in individuals and in the population as a whole. In multiparous women the most important factor was the fast fetal growth rate demonstrated in previous pregnancies. Non-smoking also made a large contribution to the LGA population (43.65%) and the risk to individual patients was doubled. The relative risk for height steadily rose with increasing stature, but the effect was much more marked for weight. Heavy women made a considerable contribution to the LGA population (26%) and the effect of increasing weight is such that very heavy women (more than +2 SD) are nine times more likely to have an LGA baby than those of average weight. The relative risk also rose sharply with increasing parity. Nevertheless, 27.5% women in our LGA group were having their first baby. The possibility that a very obese non-smoking primiparous woman may be bearing a very large baby should not be overlooked.

Changes in the oral glucose tolerance test during the puerperium

Oral glucose tolerance tests were performed during late pregnancy, on the second and fifth days of the puerperium and finally six weeks after delivery in a group of 12 healthy women. The glucose response showed no significant change from the pregnancy values on the second and fifth days of the puerperium but each woman had returned to 'normal' by the sixth week post partum. In contrast, the insulin response had returned to the non-pregnant value by the second day of the puerperium.