Right now, laptops are as popular as they have ever been. Every year, more and more families are switching from desktops to laptops because of their easy, portable usage. According to a firm called the Information Network, laptop sales reached 145.9 million in 2008. That number increased to 177.7 units sold in 2009. Demand for laptops has skyrocketed, especially in the demographic of men in their reproductive years.

Elisabeth Carlsen, M.D., of the University Department of Growth and Reproduction in Rigshospitalet, Copenhagen, and a group of three other researchers created a study to determine whether there have been any changes in the quantity or quality of sperm since the late 1930s, thinking that technology may be responsible. The team did so by comparing 61 papers including 14,947 men between 1938 and 1990. The ages of the men ranged from 17 to 64 years with a mean age between 30 and 38 years and none of the studies found any of the men to have a history of infertility. In order to downplay the effect of confounding variables in their results, Carlsen et al. used a collection of studies that used uniform sperm-counting methods. The studies they chose used different kinds of counting chambers, which is a method suggested by the World Health Organization. What they found was a substantial decrease in both sperm count and seminal volume. Sperm count decreased from 113 x 10⁶/ml in 1940 to 66 x 10⁶/ml in 1990 and seminal volume decreased from 3*40 ml to 2*75 ml over that period. The findings were recorded in the chart below.

The data suggest that the quality of semen has declined over the 50-year study period, but it is not made clear as to what is the cause of this degeneration.

In a 2011 Argentine study ran by Conrado Avendaño, Ph.D., et al., the scientists tested the hypothesis that laptops placed on laps cause a decrease in sperm quality. Two of the three negative effects that people commonly associate with laptops are that they apply heat and microwaves to the testicular region when placed on the lap. This experiment had an in vitro design using Petri dishes and samples from 29 healthy donors were utilized. The samples were divided into two parts called aliquots and for each sample, one aliquot was placed 3 cm under a laptop using wireless Wi-Fi while the other was placed into an identical environment except without the exposure to a laptop. The laptop used was a Toshiba Satellite M305D-S4829. The distance between the laptop and the Petri dish was 3 cm because that is the estimated distance between the laptop and the testes when people place laptops on their laps. After 4 hours, the samples exposed to the laptop showed a significant increase in DNA fragmentation and a significant decrease in progressive sperm motility. 80.9% of the sperm in the experimental group could not move forward after four hours whereas 68.7% of the control group’s sperm could no longer move forward. Interestingly, though, there was no significant difference in the amount of dead sperm between the control and experimental groups after the four-hour period. Also measured were the temperatures under a laptop with Wi-Fi, a laptop without Wi-Fi, and under normal conditions without a laptop. The heat coming from the wirelessly connected laptop was over 3 times higher than without Wi-Fi and 7-15 times higher than under normal conditions. Based off of this collection of results, the researchers concluded that laptop placement on the lap may lead to infertility in men.

However, there were some noticeable shortcomings to the experiment. First, only using one type of laptop can mean that the results relate to only that laptop. Perhaps a MacBook or a Dell laptop would have yielded different results. Also, the semen in the experiment was in Petri dishes as opposed to being in their natural placement in the human body. Without the protection that the tissues and fluids of the body offer, the semen could have been more prone to heat and waves emitted from the laptop.

In 2004, Dr. Yefim R. Sheynkin, M.D., of the Department of Urology at the State University of New York at Stony Brook, NY, and four other scientists performed an experiment testing the heat emitted from laptops onto the testicular region. Like the last experiment, 29 healthy volunteers ages 21 to 35 were chosen, but no semen samples were taken. Instead, right and left scrotal temperature was measured. Sheynkin et al. attached two cutaneous thermocouples (5SRTC-TT J type Teflon insulated wire to both testes to find the temperatures. For the experimental group, the participants sat with a laptop on their laps for 60 minutes and temperatures were recorded every 3 minutes. Before putting the laptops on laps, the laptops had already been turned on for 15 minutes. The control group was put under the same conditions except for the laptop. The results state that there was a significant increase in temperature in both testes when under the laptop. Both testes in the experimental group increased significantly in temperature compared to those of the control group, proving that laptops raise scrotal temperature when placed on the lap. The results are shown in the 2 charts below.

In addition to the previously stated associations between laptops and infertility, the third negative effect that is associated with laptops is the position that the laps are put in to hold the laptop. People keep their legs close together when they put a laptop on their laps, which raises the temperature in the testicular region. An increase in testicular temperature has been associated with a decrease in fertility and this sitting position adds to the heat that comes from the laptop. Two possible answers to these problems are using lap pads between our laps and laptops and making sure our legs are not too close together. Aware of these possible solutions, Sheynkin and a separate group of 5 other scientists created another experiment to evaluate the effect of leg positioning and lap pads on scrotal temperature. Using almost the exact same design of their other experiment with the same amount of participants of the same ages, the results concluded that the best combination is to sit with legs apart while using a lap pad. The scrotal temperature raised high in every 60-minute session, but it did not raise as highly with a lap pad and laps 70 degrees apart than it did with legs together with a lap pad or legs apart without a lap pad.