French researchers have published a study showing new evidence that male fertility declines as they get older. The study's authors, who published their findings in the journal Fertility and Sterility, warn that men's lack of awareness of this fact - and of their own biology - may play a part in the decline in birth rates.

The researchers, from fertility clinics across France, looked at what role the man's age played when it came to the likelihood of having children. They concluded that, similarly to women, a man's fertility begins to decline from the age of about 40. They looked at success rates in fertility treatments following treatment at 59 clinics in France, a study that included 1,938 couples. The results showed that in couples where the woman was younger than 30 but her partner was aged 40 or above, the couple was 25 per cent less likely to be successful than if the man was nearer the woman's age. Where the female member of the couple was older than 30, and her partner was 40 or above, the woman was twice as likely not to conceive.

Elise de La Rochebrochard, lead author of the study, from the French National Institute for Demographic Studies, said that the results show for the first time 'strong evidence for a paternal age effect on failure to conceive that is linked only to biological male ageing'. When it comes to reproduction she said, 'age must no longer be considered the concern of the woman, but that of the couple'.

Dr Allan Pacey, senior lecturer in andrology at the UK's University of Sheffield, and spokesperson for the British Fertility Society, said that the findings of the French researchers added to the evidence that male age was also a factor in fertility. 'Women seem to be more attuned to their biological clocks', he said, adding that 'with men, the clock seems to tick more slowly, but often I don't think they hear it at all'. The findings came in the same week as a poll in the Guardian newspaper had identified that many British couples put 'having fun' and 'having enough money to live comfortably' ahead of having children.

Reproduced from BioNews with permission, a web- and email-based source of news, information and comment on assisted reproduction and human genetics, published by Progress Educational Trust.