Researchers found men with two or more abnormalities in their semen were more than twice as likely to die over an eight year period as men who had normal semen.
The study’s lead author Dr Michael Eisenberg, assistant professor of urology at Stanford University, said smoking and diabetes – either of which doubles mortality risk – both get a lot of attention.
However he added: ‘But here we’re seeing the same doubled risk with male infertility, which is relatively understudied.’
Infertility is a widespread medical complaint in developed countries, with about one in seven couples affected at some point.
But Dr Eisenberg said his is only the third study worldwid e to address the question of a connection between male infertility and mortality.
Dr Eisenberg and his colleagues, whose findings were published online by the journal Human Reproduction, examined records of almost 12,000 men aged 20 to 50 who had visited one of two centres to be evaluated for possible infertility between 1994 and 2011.
Dr Eisenberg said: ‘We were able to determine with better than 90 per cent accuracy who died during that follow-up time.
‘There was an inverse relationship. In the years following their evaluation, men with poor semen quality had more than double the mortality rate of those who didn’t.’
While no single semen abnormality in itself predicted mortality, men with two or more such abnormalities had more than double the risk of death over the eight year period following their initial fertility examination compared with those with no semen abnormalities.
The greater the number of abnormalities, the higher the mortality rate, the study found.
Of the 11,935 men who were followed, 69 died during the follow-up period – a seemingly small number.
Dr Eisenberg said this reflects, first and foremost, their relative youth with an average age of 36.6 years.
However, he said it also reflects the fact that men who get evaluated for infertility tend to have a higher than average socio-economic status and have accordingly better diets, education and access to health care.
And Dr Eisenberg said men who are concerned about infertility are men who want to have children.
He added: ‘If you’re trying to have a child, you’re probably reasonably healthy at the moment and in mental shape to be planning for your future.’
He said, within this select group, the difference in death rates between those who had semen abnormalities and those who didn’t was statistically significant.
However, those with two or more semen abnormalities were more than twice as likely to die during the follow-up period as those without any.
Dr Eisenberg said: ‘It’s plausible that, even though we didn’t detect it, infertility may be caused by pre-existing general health problems.
‘But we controlled for this factor as best we could, and while that did attenuate the measured risk somewhat, there seems to be something else going on.
‘Could it be genetic, developmental or hormonal factors? Or could it be that something about the experience of having and raising kids – even though you may sometimes feel like they’re killing you – actually lowers mortality?’
Now Dr Eisenberg and his colleagues are trying to figure out why this is happening.
He added: ‘Is their blood pressure rising? What about their blood sugar, or other measures?
‘We are starting to do prospective data collections now, through a collaboration involving several centres.’