Researchers followed more than 135,000 older men for a decade in an effort to examine the impact of fatherhood on health.
They found that childless men and men with just one child were more likely to die from cardiovascular causes such as heart attack and stroke than men who fathered more than one child, study researcher Michael L. Eisenberg, MD, tells WebMD.
It is not clear from the study if parenthood has a direct impact on heart attack and stroke risk, or, if it does, if that impact is related to biology or differences in lifestyle.
All of the men in the analysis were married or had been married, but whether they remained childless by choice or because of infertility issues was not known.
"Surveys suggest that about 75% of childless, married men want to have children, so it may be that many of the men in our group were infertile," Eisenberg says.
He says that hormonal issues that lead to infertility may also affect heart and vascular disease risk.
Fatherhood and the Heart
Eisenberg, who specializes in male infertility and sexual dysfunction at Stanford, initiated the decade-long study while still a urology resident at the University of California, San Francisco.
Eisenberg examined data from a series of questionnaires completed by hundreds of thousands of members of AARP.
The researchers included nearly 138,000 married or previously married men aged 50 to 71.
About 11,000 of the men reported having no children. They provided no information on why they were childless, however. There was also no information on marital strain and how long children lived with fathers.
Previous studies looking at the relationship between fatherhood and death from heart disease or stroke have had mixed results. Some have shown childless men to be at higher risk for death. Other studies have shown no relationship or shown that having a higher number of children is linked to higher risk for death from heart disease or stroke.
Eisenberg says that some recent studies have suggested a link between lower testosterone levels and a higher risk for heart attack and stroke.
Eisenberg hypothesized that if the men in the study were childless or had just one child because of low testosterone, they might be more vulnerable to these cardiovascular events.
Heart Disease Risk
Over the 10 years of follow-up, about 3,000 of the men in the analysis died of heart disease or stroke. After taking into account known risks of heart disease and stroke, men with no children had a 17% increase in risk for death from these causes than men with children.
A 13% increased risk was seen among childless men compared to men who fathered just one child.
If other studies confirm a link between infertility and later cardiovascular events, Eisenberg says it might be possible to identify men at risk for heart attack and stroke years before other signs of disease are present.
But cardiologist Tara Narula, MD, tells WebMD she is unconvinced.
Narula is director of clinical cardiology at the Lenox Hill Hospital in New York City.
"We don't even know if the men in this study were infertile or if they had low testosterone," she says. "This is an interesting study that raises many questions, but really doesn't answer any."