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Serm contains a genetic "biological clock" that makes it more difficult for older men to have healthy children, research published yesterday revealed. Scientists knew that reproductive ability declines with age, as sperm becomes less plentiful and active. Now a study in the United States has found that the genetic quality of sperm also deteriorates as a man gets older.
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6 June 2006
An examination of sperm DNA from 97 volunteers aged between 22 and 80 showed that it became steadily more fragmented as age increased.
DNA fragmentation is associated with greater infertility and a reduced chance of conceiving. The sperm of older men is also more likely to carry the genetic mutation that causes achondroplasia, or dwarfism.
Since 1980, there has been about a 40 per cent increase in the number of men aged between 35 and 50 fathering children, and a 20 per cent decrease in the number of fathers under 30. Dr Andrew Wyrobek, of the Lawrence Livermore National Laboratory in Livermore, California, who led the research team, said: "This study shows that men who wait until they're older to have children are not only risking difficulties conceiving, they could also be increasing the risk of having children with genetic problems."
A woman's fertility can end abruptly about the time of the menopause.
Dr Brenda Eskenazi, a co-author of the report, said: "Our research suggests that men, too, have a biological time clock - only it is different. Men seem to have a gradual, rather than an abrupt change in fertility and in the potential ability to produce viable, healthy offspring."
The study included at least 15 men from each age decade spanning 20 to 60 years, and 25 aged 60 to 80: smokers and men who had fertility problems or a history of cancer were excluded. The findings were published in the online edition of the Proceedings of the National Academy of Sciences.
The Scotsman
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Infertility