Stuffing your phone into your pants pocket is a convenient go-to, but for men it could have dire consequences, according to research.
A new study warns that men in particular need to think twice about where they are keeping their mobile device.
A review of 21 research papers on radiation shows mobile phones kept close to a man's genitals for an extended period of time decreases sperm count.
The studies also suggest surviving sperm could be DNA-damaged.
The findings have baffled scientists who have no way to explain how non-ionizing radiation influences the body.
Without that common connection many public health investigators are not confident to say definitively that cellphones harm sperm.
But a new study, by a team at Australia's University of Newcastle, has collected years of evidence in a bid to identify the trend and find potential causes.
Statistics show that 14 per cent of the world has difficulty trying to conceive - with male infertility a factor in 40 per cent of cases.
The authors reviewed 27 studies and 21 of them showed a causal link between cellphone radiation and sperm damage.
Ten studies were looked at with 1492 human sperm samples examined.
Exposure to the mobile phones was found to be linked with a surprising 8 per cent reduction in the mobility of sperm and 9 per cent reduction in sperm viability.
The effects on the concentration of sperm were more ambiguous.
The results were consistent across all experimental laboratory studies and correlating observational studies.
The authors say they are hardly surprised by the data given the "unique vulnerability of the highly specialised sperm cell".
They said by men continuing to store their phones in their pockets, they were ignoring "the future health burden that may be created if conception proceeds with defective, DNA-damaged spermatozoa".
Dr Joel Moskowitz, of UC Berkeley's public health school, told the Daily Mail, that this review is a pivotal step towards broader global understanding about the dangers of our phones.
The World Health Organisation classified cell phone radiation as a possible 2B carcinogen.
This was the first significant recognition that cellular devices may be harmful to our bodies.
Dr Moskowitz of the University of New Castle said the review was clear evidence "men should not keep cellphones near their genitals."