According to researchers from Queen's University, Canada using your cell phone can may lower sperm quality, in turn leading to decreased fertility. Cell phone rely on electromagnetic waves (EMW) impacts levels of male hormones. Based on this research "men who reported cell phone use had higher levels of circulating testosterone but they also had lower levels of luteinizing hormone (LH). This may block the conversion of this basic type of testosterone to the more active, potent form of testosterone associated with sperm production and fertility.
While more research needs to be conducted, "mobile phone users in the UK were advised by the Government to text or use hands free kits rather than make calls.The Department of Health said this would reduce the user's exposure to reduce radiation emitted by the devices."