A new study published in Human Reproduction provides the strongest evidence yet that too much driving could be linked to infertility in men. The problem appears to be a rise in the temperature of the testicles, caused by sitting in the same position for too long.
The researchers, based in Toulouse, France, attached skin thermometer probes to the scrotums of nine men. The volunteers walked around for two and a half hours, and then drove for two and a half hours. By checking the temperature every two minutes, the team found that the men's testicles were 2.2 degrees centigrade warmer while driving than when walking.
Dr Roger Mieusset, head of the team, carried out the work after earlier studies showed that sperm counts in professional drivers are lower, and that their sperm has more abnormalities. Dr Mieusset said his results, along with data from other studies showed that the increase in scrotal temperature 'could be one of the strongest pieces of evidence yet to explain why the partners of occupational car drivers take longer to conceive'.
Dr Amin Gorgy, director of the London Fertility Centre, said it was well known that scrotal temperature affects sperm production. He advised long distance drivers to wear loose-fitting clothes, and to take regular breaks.