Dr Kirsty Horsey, Progress Educational Trust
15 February 2003
[BioNews, London]
Researchers have discovered that the quality of a man's sperm decreases with age and that the male 'biological clock' begins ticking while they are in their 20s. Men, however, lose their fertility more gradually than women.The research team, from the University of California, Berkeley, US, examined semen from nearly 100 healthy men aged between 22 and 80 for sperm volume and motility. They discovered that sperm concentration and motility decreased by 0.7 per cent. They calculated that this meant the likelihood of sperm being clinically abnormal or unhealthy is 25 per cent at 22 years old. By 30 years old, this increases to 40 per cent; by 40, to 60 per cent, and 85 per cent of sperm were abnormal or unhealthy by the age of 60.
Professor Brenda Eskenazi, from the University of California, said that the results of the study supported previous research that suggested men should consider their fertility. While the focus tended to always be on women's fertility, she said that 'men are not scot-free in this. Many of us have heard of men in their 70s and older who have kids but the probability of that happening may be lower than we thought'. The research team suggested two possible explanations for the findings - cellular or physiological changes in the genito-urinary tract that occur with age, or damage caused by longer-term exposure to external factors. For example, older men were found to be more likely to have smoked, and to have smoked for longer periods of time than younger men, and also to have had more exposure to illnesses including genitourinary infections.
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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.