THURSDAY, March 15 (HealthDay News) -- Women who deliver full-term infants with low birth weights have nearly double the risk of developing ischemic heart disease, a new study says.

These types of pregnancies may cause long-term cardiovascular changes that increase a mother's risk for heart disease, according to the researchers at the University of Texas Medical Branch in Galveston.

Ischemic heart disease affects the supply of blood to the heart.

The researchers analyzed data from more than 6,600 women who took part in the U.S. National Health and Nutrition Examination Survey between 1999 and 2006.

Ischemic heart disease occurred in 9.6 percent of women who delivered an infant that was small for their gestational age, defined as weighing less than 5 pounds, 8 ounces after 37 weeks of gestation. The rate of heart disease was 5.7 percent in women who gave birth to a normal-weight baby.

The researchers also found that having a small-for-gestational-age infant was a strong risk factor for having high blood pressure or diabetes.

"We were especially surprised that when we adjusted for family medical history and known risk factors such as smoking -- which significantly increases the risk of heart disease and low-birth-weight infants -- [having small babies] remained a powerful independent risk factor for heart disease in the mothers," Dr. Radek Bukowski, a professor of obstetrics and gynecology at the University of Texas Medical Branch, said in a university news release.

The study was published in the March 14 issue of the journal PLoS One.

The findings provide new information about the suspected link between low-birth-weight infants (which account for about 10 percent of births) and increased risk of ischemic heart disease among mothers, according to the news release. Until now, it was believed that this association was due to common genetic or environmental factors, or to poor overall health.

"What we found instead is that pregnancies that produce small infants may trigger long-term cardiovascular changes that increase the mothers' risks for heart disease," Bukowski said. "If future research confirms birth weight as a solid predictor, we will have a low-cost, effective method to improve identification of women at risk and potentially help prevent heart disease decades before women experience trouble."

Heart disease is the leading cause of death among women in the United States; nearly one in three deaths are caused by the disease.

Although the study found an association between babies' birth weight and mothers' heart disease, it did not prove a cause-and-effect relationship.

More information

The U.S. National Heart, Lung, and Blood Institute has more about women and heart disease.