Men who have a history of smoking cannabis have higher sperm counts and fertility than those who don’t.
The result came as a big surprise to scientists measuring the fertility of more than 600 men from couples attending a clinic.
They expected cannabis to have a detrimental effect on sperm count and fertility.
Instead, those participants who admitted ever taking the drug turned out to have higher sperm counts than non-users.
The finding does not necessarily mean that smoking cannabis increases the chances of fatherhood, the study authors and other experts were quick to point out.
There could be a non-causal explanation for the association, such as the effect of the male hormone testosterone on both sperm count and risk-taking behaviour such as smoking cannabis.
US lead researcher Dr Jorge Chavarro, from the Harvard TH Chan School of…