In one ejaculate, the number of sperm can range from 50 – 600 million. Why so many? Because sperm are sensitive! It doesn't take much to cut down their numbers and it takes very little to interfere with their motility (swimming ability). Though the effect of laptops on sperm is not fully known, the research seems to indicate that heat from laptops can lower sperm count. So far, it is not known whether or not laptop use could cause irreversible infertility.
There have been few studies conducted on sperm count and laptop use, but these few indicate that using a laptop on one's lap with legs crossed can raise the scrotal temperature by as much as 5 degrees Fahrenheit. Using a laptop pad can reduce the increase, but only by a very small amount. Keeping legs apart was found to reduce the increase most significantly, by about 2 degrees.
The testicles are about 5-7 degrees Fahrenheit cooler than the rest of the body because they are situated outside the body. An increase in the temperature of the testes may cause oxidative stress, slow the motion of sperm, kill sperm, and lessen the ability of sperm to fertilize an egg for weeks or months. Some fertility studies have shown that an increase in scrotum temperature by 2–3 degrees Fahrenheit can reduce sperm count by as much as 40%. Others have not found as dramatic of a reduction, but researchers believe that 2.5 degrees Fahrenheit (1 degree Celsius) is the threshold for the impairment of fertility.
What about that other very common device, the cell phone? Some men store their phone in the front pocket or clipped to the waist of their pants. Research has found that the electromagnetic radiation emitted by cell phones while in use (i.e., not on standby mode) caused lower sperm mobility and lower sperm viability (% of live sperm). So talking on the phone with that hands-free device may not be all that much healthier for you if your phone is in your pocket or clipped to your waist during the conversation. It is not currently known how cell phones in standby mode affect fertility and it is also not currently known how laptops or cell phones might affect women's reproductive systems.
In general, laptops (and cell phones) do not seem to represent very large risk factors for infertility, and what damage they do cause is likely to be reversible. However, researchers have not ruled out the possibility that extended periods of exposure could cause permanent infertility, so it may be worth using a laptop pad or table if you're surfin' the web for an extended period of time every day.
Many other factors can affect sperm count and motility. For more information, check out some of the Q&As below.Alice!