According to a study by New Scientist magazine, heated seats can raise testicular temperatures enough to inhibit fertility--in much the same way a hot tub soak can kill off active sperm cells.
Some 30 German men were studied, and the results published in the Fertility and Sterility medical journal say heated seats could raise temperatures in the scrotum to 37.3 degrees--while 35.5 degrees Celsius is the optimum baby-making temperature. In the study, one man's vitals were gauged at 39.7 degrees C.
Scientists say the differences may seem small, but the rise in temps could be enough to put a damper on sperm production and motility. It's the same as if the men worked in a hot factory or drove a taxi all day, they noted.