MONDAY, Sept. 26 (HealthDay News) -- Men who do not have children appear to face a higher risk of dying from heart disease than those who become fathers, a new study suggests.

The findings also showed a slightly increased risk of cardiovascular trouble among men who had only one child. The researchers noted that the results may indicate a link between infertility and heart disease risk rather than a link between choosing not to have children and heart disease.

In the study, researchers analyzed more than a decade's worth of survey responses completed by roughly 135,000 male AARP members. The men were either married or had been married, and none had a prior history of heart disease or stroke.

Researchers tracked deaths and cause of deaths, and correlated that to the number of children the men had.

About 10 percent of the men died during the study period, including about 20 percent from heart disease.

After accounting for a wide range of factors such as race, cigarette and alcohol use, education and income status, age, exercise habits and body-mass index, researchers found that men who had no children had a 17 percent higher risk of dying from heart disease.

While the study found an association between childlessness and heart disease, it did not prove a cause and effect.

Researchers used married men as a "rough proxy" for men who had the opportunity to have children and wanted to have children, while the number of children men had was an indicator, albeit not a perfect one, for a man's fertility.

"This opens up a window into men's health," suggested study author Dr. Michael L. Eisenberg, an assistant professor in the department of urology at Stanford University in Palo Alto, Calif. "It shows that fertility may protect against later health problems. And if so it could mean that when men seek medical attention for infertility, which is often the first time they seek medical attention for anything, we could have a unique opportunity to intervene and help with their overall health."

And yet, researchers acknowledged neither marital status nor number of children was a precise measure of infertility. None of the men were actually screened for infertility status or other physiological markers for infertility, such as fluctuating testosterone levels.

So, while shared biological factors such as hormone deficiencies could be driving both childlessness and heart disease death risk, it's also possible that other environmental/behavioral issues might also contribute, researchers said.

For example, the authors noted that men who have children may end up embracing healthier lifestyles, thereby lowering their risk for heart disease.

"And it is certainly the case that things that are good for fertility are also going to be good for your heart," said Eisenberg, a urology resident at the University of California, San Francisco, when he did the study. "Good exercise habits, a good diet, maintaining a healthy weight, not smoking. All these things can impact both."

Researchers also stressed that their findings show an "association" between being childless and having heart disease, rather than cause-and-effect.

The study is published in the Sept. 26 online edition of Human Reproduction.

The authors pointed out that more than one-third of the human genome is involved in the process of reproduction. That fact led the team to theorize that fertility status might be significantly correlated with a man's long-term health and disease status.

Dr. Robert Myerburg, a cardiology professor at the University of Miami Miller School of Medicine, called the findings "compelling," but said childless men shouldn't worry.

"Given the large population they looked at, I think they have identified an association that is worth exploring," he noted. "And there may certainly be clues about what's going on here that are interesting and should be examined. But this is going to take a lot of studying for a very long time."

And, he noted, "population risk is not always the same as individual risk -- an 18 percent higher mortality risk among a group of childless men does not actually mean that any one childless man will face a noticeably higher risk. There might, in fact, be no consequences, especially if an individual's risk is very low to begin with. So while this research continues, childless men should not view these findings with alarm."

More information

For more on infertility, visit the U.S. Centers for Disease Control and Prevention.