Sperm out for the count

A new study of men attending a Scottish fertility clinic indicates a general decline in sperm count. The SPIN (Semen Parameters in the Northeast) study measured the sperm count in over 16,000 semen samples from over 7,500 men attending the Aberdeen Fertility Centre between 1989 and 2002. The findings showed a drop of almost 30 per cent in the average sperm concentration.

Within the study group, the average sperm count of men who had a 'normal' sperm concentration (those with more that 20 million sperm per millilitre (ml)) fell from nearly 87 million sperm per ml to just over 62 sperm per ml, a 29 per cent decline in average sperm numbers, although still well within the 'normal' range. The results of the study were presented at the joint meeting of the Association of Clinical Embryologists and the British Fertility Society, held in Liverpool from 5-6 January 2004.

Dr Siladitya Bhattacharya, leader of the research team, said that the results could not be used to determine a fall in levels of male fertility and that there were many different reasons why fertility levels may be dropping. She did say that there had been an increase in men coming forward to be treated for male infertility, but added 'whether this is due to a significant increase in this condition or because men are more aware of new techniques which have been developed to help them, we couldn't say'. 'We look forward to collecting data on other aspects of sperm quality to see if there is a similar decline', she added.

In another study, published towards the end of 2003, US researchers found that the quality of men's sperm declined as they aged. Narendra Singh and colleagues from the University of Washington in Seattle tested 66 men aged between 20 and 57 years old. The researchers, who published their findings in the journal Fertility and Sterility, found that the older men get, the more genetically damaged their sperm is likely to be. Higher levels of DNA damage means that sperm are less likely to undergo apoptosis, a natural self-destruct process designed to get rid of damaged cells. But what the study cannot show, says the research team, is whether increased damage arises because of chronological age or because of longer-term exposure to environmental factors that may cause damage.