Men have biological clock too, claim researchers

Men have biological clock too, claim researchers
Biological clocks are found in men as well as women, according to new research that found male fertility begins to decline when they reach their mid-30s.

By Ben Leach
Last Updated: 7:50PM GMT 26 Oct 2008

Scientists said men who wait until their 40s before starting a family face a greater chance of their partner having a miscarriage, because of the poorer quality of their sperm.

"Drops in fertility from the age of 35 have been traditionally thought of as a fact-of-life for women but our study shows the same is true for men," said Dr Mark Bowman, the director of a Sydney IVF clinic which carried out tests on 3,324 men over four years.

Their sperm DNA was tested to assess its "reproductive potential". The study showed that from the age of 35, the proportion of damaged sperm increased.

Dr Bowman added: "This means that even if a man produces the average of 40 million sperm per ejaculation, many of those sperm will not be able to fertilise an egg normally. He will have a lower fertility potential and be less likely to father a child."

The study is further evidence that men have a biological clock.

Earlier this year a study of more than 20,000 couples seeking fertility help found that middle-aged men are almost a third less likely to conceive with their partner than males under 35.

Doctors have long warned that too many young women are putting off starting a family until their late thirties or early forties, by which time their fertility levels have started to fall.

But the example of older celebrity fathers, including Sir Paul McCartney and Rod Stewart, may have encouraged many men to believe that they can postpone having children for much longer than women.

The research at the Eylau Centre for Assisted Reproduction in Paris found that the older a prospective father, the less chance that their partner would become pregnant. The study involved a form of fertility treatment, where the sperm is "washed'' before being inseminated into the woman. This helps the sperm to survive for longer.

For men between 30 and 35 the successful pregnancy rate was 13.6 per cent. But that fell to 9.3 per cent if the man was older than 45, a decrease of almost a third

The findings also showed that men over 35 were 75 per cent more likely to have their partner suffer a miscarriage. Although lower than the miscarriage rate for older mothers, which was more than twice that of younger mothers, the researchers still described it as significant.

They believe there could be a number of reasons behind the findings, including that the DNA of sperm decays over time.