Hot Seats, Laptops, Cell Phones and Sperm

Every man who has put on an athletic supporter must have wondered why his "family jewels" are suspended in such a vulnerable position. Why hasn't nature tucked the testicles into the protective confines of the pelvis like their female counterparts, the ovaries?

The simple reason is temperature. Low temperature is essential for sperm production. But modern conveniences may warm things up or have other unintended effects on testicular function. Here's some interesting research that gives global warming a new meaning:

Sperm and temperature

Early in embryonic life, the testicles are positioned deep in the rear of the abdomen. But at about 17 weeks of pregnancy, the testicles begin to gradually descend through the abdomen. They arrive at the groin five to 10 weeks later and then cross into the scrotum by the 30th week of pregnancy.

Whether a man is hot or cool, his scrotal temperature averages about 6 degrees Fahrenheit below his internal body temperature. When conditions are right, a young man's testicles can crank out up to 1,000 sperm a second. But at warmer scrotal temperatures, sperm production slows, sometimes impairing fertility.

Prolonged sitting

Both men and women have many good reasons to be up and around. But gents of reproductive age have extra motivation. Simply sitting in a car for two hours increases scrotal temperature by about 4 degrees Fahrenheit. The effect is temporary, but men who average more than three hours a day driving take longer to father children than their peers who spend less time sitting in a car.

Hot seats

A heated car seat feels mighty good on a wintry day, but can it add fuel to the fire of scrotal warming? To find out, doctors in Germany studied 30 healthy volunteers ages 20 to 53 who were dressed in boxer shorts, trousers and shirts during the experiment. Each man spent 90 minutes sitting on either a heated or unheated car seat while his scrotal temperature was recorded at one-minute intervals. Even sitting still on an unheated car seat boosted scrotal temperature, but the heated car seat added about 1 degree Fahrenheit without significantly increasing internal body temperature.

Laptop computers

Laptop computers are hot items—so hot, in fact, that their internal operating temperatures top 158 degrees Fahrenheit. Most men use their computers on a desk or table. But what if these marvelous devices are taken literally and used on a man's lap?

American scientists looked to answer the question by asking 29 healthy volunteers ages 21 to 35 to spend 60 minutes sitting with or without a working laptop perched on their thighs. The bottom surface of the laptop heated up to about 104 degrees Fahrenheit by the end of the hour. Sure enough, scrotal temperatures rose by about 1 degree Fahrenheit more than with sitting alone.

These studies show that the heat generated by electrical devices that we take for granted can significantly increase scrotal temperatures. They also remind us that simply sitting still for an hour or longer can raise scrotal temperature, though to a lesser degree. These short-term experiments did not evaluate sperm counts, semen quality or fertility, but other investigations suggest that scrotal warming can have an adverse effect on fertility.