March 14, 2012 -- Women who give birth to small, full-term babies may have an increased risk for heart disease decades later, new research shows.

Delivering a small baby was found to be a strong, independent predictor of heart disease later in life in a new study led by researchers from the University of Texas Medical Branch in Galveston.

After accounting for medical and genetic factors that influence heart risk, the researchers found that women who had smaller babies were almost twice as likely to develop heart disease an average of three decades later.

About 1 in 10 full-term births involve small-for-their-gestational-age (SGA) babies.

If the findings are confirmed, asking women if they have had an SGA baby could prove to be a simple, low-tech way to help identify those at risk for heart disease decades before symptoms appear, the researchers say.

“Women tend to be pretty good at remembering how big their babies were at birth,” University of Texas ob-gyn professor Radek Bukowski, MD, tells WebMD.

Do Small Babies Trigger Heart Changes?

Bukowski says pregnancies that result in small, full-term babies may trigger blood vessel changes that increase the mother’s long-term risk for heart disease.

In the new study, published in the journal PLoS One, Bukowski and colleagues analyzed data from a nationally representative sample of some 6,600 women surveyed between 1999 and 2006.

The women, who were participants in the National Health and Nutrition Examination Survey (NHANES), provided information about their heart disease histories along with their risk factors for heart attack and stroke.

They were also asked about their childbirth histories.

An SGA birth was defined as delivering a baby weighing less than 5 pounds, 8 ounces at a gestational age of 37 weeks or more.

The odds of developing a heart attack or coronary artery disease were found to be almost two times higher among women who delivered a small, full-term baby than among women who had not (9.6% vs. 5.7%).

The researchers found that this risk was comparable to other risk factors for heart disease such as high blood pressure and diabetes.

Delivery of an SGA baby preceded the diagnosis of heart disease by an average of three decades.

Predictive Value of SGA Birth Unclear

It is not clear how delivering a small, full-term baby might influence heart disease risk.

One theory, Bukowski says, is that low concentrations of factors that stimulate placental growth could also inhibit the growth of blood vessels that repair the heart. If this is true, then such a deficiency could permanently affect heart circulation.

While she calls the findings intriguing, cardiologist Tara Narula, MD, of Lenox Hill Hospital in New York City, says it is premature to conclude that giving birth to an SGA baby directly influences heart disease risk.

“To come to the conclusion that something about having an SGA baby increases a woman’s risk for developing heart disease later in life is a big leap,” she tells WebMD.

She points out that guidelines already recommend asking women about their childbirth history when assessing their risk for heart attack and stroke.

“Women tend to [show symptoms of] heart disease later in life than men,” she says. “I think the overall concept of looking for ways to predict heart disease at an early age is a great one. But more study is needed before we will know if this approach will help do that.”