Gestational diabetes develops only during pregnancy and typically goes away after pregnancy. It does, however, increase a woman's risk for type 2 diabetes in future years.
The new study found that gestational diabetes might also increase a woman's risk of heart disease in midlife and before she develops diabetes or metabolic syndrome, a group of symptoms and conditions known to increase the chances of heart troubles.
The study included nearly 900 women, aged 18 to 30, in the United States who had one or more pregnancies and were followed for 20 years. Of those women, 13 percent developed gestational diabetes.
The thickness of the women's neck (carotid) arteries was checked an average of 12 years after pregnancy, when they were aged 38 to 50. Thickening of the neck arteries -- called atherosclerosis -- is an early sign of heart disease.
Among women who did not develop diabetes or metabolic syndrome during the 20 years of follow-up, those who had gestational diabetes had greater thickness in their neck arteries than those who didn't have gestational diabetes.
The study appeared March 12 in the Journal of the American Heart Association.
"This finding indicates that a history of gestational diabetes may influence development of early atherosclerosis before the onset of diabetes and metabolic diseases that previously have been linked to heart disease," lead author Erica Gunderson, a senior research scientist at Kaiser Permanente Northern California, said in a journal news release.
"Gestational diabetes may be an early risk factor for heart disease in women," she said.
The study found an association between pregnancy-related diabetes and heart disease risk. It did not prove cause-and-effect.
The U.S. National Heart, Lung, and Blood Institute has more about heart disease in women.