Men without children are more likely to die from heart disease than fathers, a study has shown.
The finding may reflect links with infertility, hormone levels or behaviour, say the US researchers.
Scientists analysed data on 135,000 married or formerly married men over the age of 50 and tracked their health progress for 10 years.
They found that those who never had children were 17% more likely to die from a heart condition than men who became fathers.
Remaining childless could be an indicator of infertility in a group that excluded bachelors, said the researchers. However, it was not possible to say that infertility led directly to a heightened risk of death from heart disease.
The findings are published in the latest online edition of the journal Human Reproduction.
Adjustments were made to take account of influences such activity levels, health status, body weight, tobacco and alcohol use, race, age, household income and education.
All the men were in good health at the start of the research and had no previous history of heart disease, stroke or related conditions.
Over the course of the study, around 10% of the men died.
Although a higher overall risk of dying was seen in childless men, only the increased rate of heart disease death was significant.
A possible causal link with infertility needed further investigation, said the scientists.
Lead researcher Dr Michael Eisenberg, from Stanford University School of Medicine in California, said: "Is there a real biological cause behind both? Maybe we should look closer at the childless group."
The male hormone testosterone could also play a role in the association, according to the scientists.
A recent study of 600 Filipino fathers found that men with high testosterone levels were more likely to become fathers. Once they became parents, their testosterone levels fell.
Low initial levels of testosterone may be linked to greater heart disease risk in later life, as well as impacting on fatherhood, said the researchers.
On the other hand, being fathers may simply cause men to look after their health more.
"Maybe having children causes men to have healthier behaviours, so fathers will live longer," Dr Eisenberg added.