Women who deliver their babies prematurely appear to be at a greater risk of cardiovascular disease later in life, according to a new study.

Heart disease is the leading cause of death for women as well as men in the United States – accounting for about 1 in every 4 deaths, according to the Centers for Disease Control and Prevention.

Experts say the new findings, published in the American Heart Association’s “Go Red for Women” issue of the journal Circulation, can help provide women and their doctors with an indicator that they may be high risk for heart disease.

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“A woman who delivers a preterm infant now has an early warning signal for her future health,” Lauren Tanz, first author of the study and a programmer and analyst at Brigham and Women’s Hospital in Boston, told CBS News. “Since heart disease risk develops over a lifetime, she might want to adopt a heart healthy diet and lifestyle.”

Specifically, the results showed that women who have delivered prematurely — before 37 weeks — have a 40 percent increased risk of eventually developing heart disease when compared to women who had their babies after 37 weeks. Women who delivered their babies before 32 weeks had double the risk of cardiovascular disease.

Previous studies have shown preterm delivery to be associated with a higher risk of heart disease, but they did not separate whether the risk remained after adjusting for a woman’s pre-pregnancy lifestyle and risk factors for cardiovascular disease.

“What’s most interesting about this study is that this wasn’t explained in most of these cases by standard risk factors. Things like preeclampsia, blood pressure, diabetes, all of those things that we usually say lead to heart disease. “This was independent of these risk factors,” Dr. Suzanne Steinbaum, director of women’s heart health at Lenox Hill Hospital/North-Shore LIJ in New York and a “Go Red for Women” spokesperson, told CBS News.

The researchers used data from the long-running Nurses’ Health Study II and reviewed information on more than 70,000 women. They adjusted for a number of risk factors including age, race, parental education, and pre-pregnancy lifestyle.

The results showed the risks were stronger for women who delivered more than one preterm baby. The elevated risk held true even for preterm deliveries that were not complicated by hypertensive [high blood pressure] disorders of pregnancy, such as preeclampsia.

Experts say more research is needed to figure out what is behind the connection between preterm delivery and heart disease risk.

“Our hypothesis behind this is that preterm delivery is an early warning sign of some clinical cardiovascular risk that is present before or at the time of the pregnancy,” said Tanz, who is also a doctoral student at the Harvard T.H. Chan School of Public Health. “So the preterm delivery is unveiling that risk.”

Steinbaum says having this kind of indicator early in a woman’s life is extremely beneficial for physicians, so they can provide at-risk women with appropriate interventions sooner rather than later.

“What this provides us is another insight and another way to assess women earlier in life to try to early-prevent, early-diagnose, and early-treat, and really focus on those women who are at risk for heart disease to prevent it from ever happening,” Steinbaum said.

Women who have delivered preterm, she said, should take steps to protect their hearts with a healthy lifestyle and early and regular checks for heart disease risk factors such as blood pressure and cholesterol.

“Many times people think of heart disease as an elderly person’s disease but in fact what we’re understanding more and more, especially in women, is that heart disease develops throughout life,” Steinbaum said. “It takes decades. And pregnancy and delivery may be the first insight we get as to who’s at risk later in life.”