Some scientific studies have suggested that the radio frequencies used by mobile phones could have deleterious effects on health, such as a decrease in sperm quantity and quality.
However, not all studies present the same results. This may be due to the presence of confounding factors, such as has happened in the case of coffee, which has been associated in some studies with lung cancer.
The conclusion is that as of today we cannot ensure with certainty that the use of a mobile phone affects sperm quality. However, there are studies that suggest it and it seems reasonable to recommend to patients who have sperm problems or who are going to undergo fertility treatment, that as far as possible, they do not abuse the use of these devices.