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Tuesday, 30 May, 2000, 23:59 GMT 00:59 UK
Driving linked to infertility
HGV drivers may be at risk
Scientists have uncovered a risk factor for fertility - spending too long behind the wheel.

The problem appears to be that sitting in the same position for an extended period of time leads to a rise in the temperature of the scrotum.

It is well known that sperm production falls off if the environment within the testicles becomes too hot - that is why they are housed outside the main part of the body.

Previous research has shown that men who drive for a living have a lower sperm count, more sperm abnormalities and that their partners take longer to conceive.

But scientists have not known why truckers and other professional drivers have more fertility problems.

A study by French researchers, published in the journal Human Reproduction, is the first study to provide some of the answers.

Researchers in Toulouse attached skin thermometer probes to the scrotums of nine men who first walked in the open air and then drove for 160 minutes in a car.

During the first 20 minutes of driving, the men's average scrotal temperature rose from 34.2 degrees Celsius to 35.5 degrees Celsius.

Over the next two hours the scrotal temperature rose to 36.2 degrees Celsius before stabilising.

The average temperature while driving was 2.2 degrees higher than when the men were walking.

Strong evidence

Head of the research Dr Roger Mieusset said: "Taken together with the data from other studies, the increase in scrotal temperature we measured in these drivers could be one of the strongest pieces of evidence yet to explain why the partners of occupational car drivers take longer to conceive.

"While the scientific background suggests that an increase in scrotal temperature affects sperm formation, we need more research to confirm the possibility.

"However, our results indicate that male reproductive function is vulnerable from lifestyle factors."

Dr Amin Gorgy, clinical director of the London Fertility Centre, said: "It is well known that scrotal temperature affects the function of the testes and spermatogenesis (sperm production)."

He said that was why men whose testicles had failed to descend properly during childhood were more prone to be infertile in later life.

Dr Gorgy advised long distance drivers to wear loose-fitting clothes, and to take regular breaks.

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02 Jan 00 | Health
Hope for infertile men
17 Mar 00 | Health
Modern man still virile
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