Men who never have children have a higher risk of dying from cardiovascular disease than men who are fathers, according to a large study led by the Stanford University School of Medicine.

The research, published online in the journal Human Reproduction, tracked about 135,000 male members of the American Association of Retired Persons (AARP) over a decade in order to determine how children influence a man's long-term health.

This was the largest-ever study in the United States to examine the relationship between fatherhood and cardiovascular disease, Dr. Michael Eisenberg, an assistant professor of urology at Stanford, said in a statement.

To ensure the men involved in the study had both the intent and opportunity to reproduce, Eisenberg and his colleagues restricted their subject to those who were either married or had been married in the past. At the start of the study the men -- who were at a median age of 62.7-years-old -- had never been diagnosed with heart disease or stroke. More than 9 out of 10 of the men had fathered children.

Eisenberg, who specialize in male infertility and sexual dysfunction, suspects infertility might be an indicator of other health problems in men. Therefore, he and his colleagues used the number of offspring each study participant had as a stand-in for whether they were infertile. While some of the men may have remained childless by choice, the researchers cited a nationwide survey of childless married U.S. men of reproductive that found three out of four wanted kids.

Over the course of the study, about 10 percent of the men died, with one in every five deaths attributable to cardiovascular disease. After accounting for socoiodemographic factors such as education and heart disease risk factors, the researchers determined that men who never reproduced were 17 percent more likely to have died of heart disease than those who had even one child.

A lot of times when we see men for infertility, they're very young, Eisenberg told MSNBC. A lot of these men are totally healthy. It's sort of eye-opening to hear there could be something else going on.

For instance, the study authors suggest that low testosterone level may impair male fertility and could lead to a higher risk of heart disease later in life. However, the team emphasized that hypothesis should not be confused with another recent study that found that fertile men's testosterone levels drop when they become fathers.

Simply having children in itself could prolong life, according to Eisenberg, since other research has shown that men live longer when they don't live alone.

Maybe having children causes men to have healthier behaviors, so fathers will live longer, he said.