Back in 2004, a study at the Aberdeen Fertility Centre, University of Aberdeen, published in journal Human Reproduction, found that sperm counts fell by nearly 30 percent among a test group of 7,500 men between 1989 and 2002, which suspiciously coincides with the growing popularity of laptop computers over the same time envelope.
Now new research by the State University of New York found that scrotal temperature in study participants using laptops on their laps increases by up to 2.5° C. Although the subjects did not feel the increase, it is deemed "unsafe" by study team leader urologist Yelim Sheynki.
Laptop users who insist on using laptops on their laps are advised to use a lap mat. One important feature is to have a lap pad or lap desk wide enough (eg: http://laptopdesk.net/http://laptopdesk.net/ ) that the user can relax his knees naturally instead of squeezing them together to balance and support a slippery, narrow laptop.
Another is for the device to be either insulated (example: X-Pad - http://www.xpad4laptop.com/index.html ) or feature enhance convection cooling thereby lowering the amount of heat transferred downward - preferably both -or to have active cooling fans (Targus Chill Mat), that scavenge heat and blow it away from the computer and your lap.
The university's troubling findings are published in the November 2010 issue of "Fertility and Sterility" which you can buy here.