Clinical

Gestational hyperglycemia increases risk of adverse pregnancy outcomes

Last Updated: 2008-05-07 17:00:17 -0400 (Reuters Health)

By Karla Gale

NEW YORK (Reuters Health) - Maternal blood glucose levels above normal but below those diagnostic of overt diabetes are associated with adverse pregnancy outcomes, including macrosomia, cesarean delivery, and birth injury, a multinational research team reports in the New England Journal of Medicine for May 8.

"One goal of our study was to establish whether the risks associated with gestational diabetes are really associated with blood sugar levels, or if they are related to other confounding factors, such as obesity, older maternal age, or hypertension," Dr. Boyd E. Metzger told Reuters Health. "If the answer is 'yes, blood glucose level does affect outcome,' then we need to know, how high does it need to be before the risk is present?"

The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study included data from nearly 24,000 pregnant women in nine countries who underwent 75-g oral glucose-tolerance testing between 24 and 32 weeks of gestation. Subjects with test results diagnostic of diabetes were excluded.

The results demonstrated a continuum of risk, without clear thresholds, between carbohydrate intolerance in pregnancy and adverse pregnancy outcomes.

For increases of one standard deviation in fasting and 1- and 2-hour plasma glucose levels, the risks of birthweight > 90th percentile and cord-blood serum C peptide levels > 90th percentile were increased by about 40%, after controlling for multiple confounders.

Primary cesarean delivery, neonatal hypoglycemia, premature delivery, shoulder dystocia or birth injury, intensive neonatal care, hyperbilirubinemia, and preeclampsia also showed continuous linear associations with glucose test results.

The question remains, Dr. Metzger said, "at what level of risk should we intervene? That is a big question that can't be addressed by this research."

He noted that a meeting to discuss these issues is scheduled next month immediately following the annual meeting of the American Diabetes Association.

N Engl J Med 2008;358:1991-2002.