Well, guys, now you have an excuse for sitting around with your legs wide apart in that way that irritates the opposite sex so deeply.
It seems that using a notebook on your lap, even with a cooling pad underneath can damage sperm - as long as your legs are together.
Writing in Fertility and Sterility, a group of urologists from the State University of New York recorded the temperature of 29 laptop-using volunteers' scrotal sacs - nice work if you can get it, say we.
The men worked on a laptop for three separate sessions of an hour each; one with their legs close together, one with legs close together plus a cooling lap pad, and one using the lap pad but with legs 70 degrees apart.
They found that for all three sessions scrotal temperature rose.
However, the increase was substantially lower for the chaps letting it all hang out, at about one and a half degrees C. Keeping the legs close together but using the lap pad raised temperatures by a little over two degrees, while legs together without a lap pad brought a temperature rise of around two and a half degrees.
A scrotal temperature elevation of one degree C was reached at 11 minutes in the first session, 14 minutes in the second and 28 minutes in the third.
A rise in temperature of a couple of degrees might not seem much - in fact, it sounds rather cosy. But previous studies have shown that it's enough to damage sperm quality.
"Sitting position with closely approximated legs is the major cause of scrotal hyperthermia. Scrotal shielding with a lap pad does not protect from scrotal temperature elevation," conclude the researchers.
"Prevention of scrotal hyperthermia in LC [laptop computer] users presently is not feasible. However, scrotal hyperthermia may be reduced by a modified sitting position (legs apart) and significantly shorter use of LC."