Men who have smoked marijuana may be more fertile and have a higher sperm count according to a new study published in the journal Human Reproduction.
Scientists found there was no significant difference in sperm concentrations between current and former smokers.
The result came as a big surprise to scientists measuring the sperm counts of more than 600 men from couples attending a fertility 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.
Co-author Dr Jorge Chavarro, an associate professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health says that given those links, they expected to find that men who have smoked pot would have worse measures of fertility but the data suggested the opposite.
'We spent a good two months redoing everything, making sure that there wasn't any error in the data,' Cahvarro was quoted by Bloomberg.
He added; 'We were very, very surprised about this,'
WORSE SEMEN QUALITY
The researchers expected that smoking cannabis would be associated with worse semen quality, as historical studies had suggested the drug has negative effects on reproductive health.
Many of the older studies had focused on animal models or had examined men with histories of drug abuse.
In the new research 1,143 semen samples were collected from 662 men between 2000 and 2017.
The researchers have cautioned that there are limitations to the findings, as some of the participants may have under-reported their cannabis use.