Researchers in Argentina took sperm samples and exposed half the sample to a wi-fi connection for about 4 hours. The other half was kept out of the wireless range, but otherwise treated in the same way.
The exposed sperm “showed a significant decrease in progressive sperm motility and an increase in sperm DNA fragmentation.” The researchers “speculate that keeping a laptop connected wirelessly to the internet on the lap near the testes may result in decreased male fertility.” Of course, they say further study is needed to prove this possibility.
If you're using a wireless connection to the Internet to read this and you're a male trying to have a child, you may want to shift to a cable connection just in case.
The complete article -- C. Avendaño, A. Mata, C.A. Sanchez Sarmiento, G.F. Doncel. Use of laptop computers connected to internet through Wi-Fi decreases human sperm motility and increases sperm DNA fragmentation. Fertility and Sterility 2012 (97): 39-45.e2. – is at: http://www.fertstert.org/article/S0015-0282%2811%2902678-1/abstract