Men who have been diagnosed with poor sperm quality and who are trying to have children may  wish to limit their cell phone use. Rany Shamloul, from Queen’s University (Canada), and colleagues report that  while cell phone use appears to increase the level of testosterone circulating in the body, it reduces the levels of luteinizing hormone (LH), an important reproductive hormone that is secreted by the pituitary gland in the brain. The researchers hypothesize that electromagnetic waves (EMW) emitted by cell phones may have a dual action on male hormone levels and fertility. EMW may increase the number of cells in the testes that produce testosterone; however, by lowering the levels of LH excreted by the pituitary gland, EMW may also block the conversion of this basic circulating type of testosterone to the more active, potent form of testosterone associated with sperm production and fertility. Writing that: Our results showed that cell phone use negatively affects sperm quality in men,” the team urges for: “Further studies with a careful design are needed to determine the effect of cell phone use on male fertility.”