Carbohydrate intolerance in pregnancy: incidence and neonatal outcomes

To determine the incidence of carbohydrate intolerance during pregnancy and its impact on neonatal outcomes, which have not been formally established in Canada.

Chart review.

All 1432 women who delivered a single newborn in the months of May and September 1992 in Hôpital Sainte-Justine, Montreal, Hôpital Maisonneuve-Rosemont, Montreal, and Centre hospitalier de Rouyn-Noranda, Rouyn, Que. Women with multiple births or pre-existing diabetes mellitus were excluded.

Carbohydrate intolerance, including gestational glucose intolerance (one abnormal result of an oral glucose tolerance test) and gestational diabetes mellitus (two or more abnormal results of the test); neonatal outcomes, including birth weight, hypoglycemia and hyperbilirubinemia.

Of the 1074 women tested, 72 (6.7%) had gestational glucose intolerance and 98 (9.1%) had gestational diabetes mellitus. Of those women with carbohydrate intolerance, 120 were treated and 50 were not. Women who were not treated had higher rates of poor neonatal outcomes than women without carbohydrate intolerance (p < 0.05) or than women with carbohydrate intolerance who had received treatment (p < 0.05). Women who were not treated had higher rates of newborns with a birth weight of more than 4000 g (18.0%), large-for-gestational-age newborns (20.0%) and newborns with hypoglycemia (24.0%) or hyperbilirubinemia (40.0%) than women without carbohydrate intolerance (for whom the rates were 6.7%, 10.0%, 10.0% and 22.8%, respectively) or than women with carbohydrate intolerance who received treatment (for whom the rates were 6.7%, 6.7%, 10.0% and 21.7%, respectively).

In this population, carbohydrate intolerance during pregnancy is a significant problem. Not only is the incidence rate higher than that usually estimated, but the impact on neonatal morbidity is also significant.