U.S. researchers acknowledge that new study results should not be considered irrefutable, but they still offer some guidance about whether or not men should be consuming cannabis if trying to start a family.

Noting that cannabis consumption is common among men presenting for a fertility evaluation, the investigators suggest using weed “may have a detrimental effect on semen quality, particularly morphology and volume.”

To assess if marijuana consumption plays a role in changing semen parameters, input was received from 409 patients at one institution from July 2017 to April 2018 who completed a questionnaire. Researchers then carried out semen analyses (SA) — considering such factors as volume, concentration and motility — from the men presenting for infertility evaluation.

Of the group, 43 per cent of the men reported using cannabis currently or in the past. THC “can alter signalling pathways within spermatozoa, affecting spermatogenesis and fertility,” investigators write.

The research article detailing findings, published in Therapeutic Advances in Urology, shows current or past cannabis users “had a significantly higher likelihood of abnormal sperm strict morphology” compared to those who abstain.

Indeed, this abnormality was present in just 33.1 per cent of never-users, far lower than the 50.7 per cent in current users and 53.4 per cent in past users.

With regard to past users having more of this characteristic, study authors suggested that might be caused by “a delayed negative effect of marijuana on sperm morphology,” according to IFL Science.

So, too, was semen volume less than the World Health Organization (WHO) reference value, the study results show.

Even so, cannabis use did not seem to negatively influence motility. “Sperm motility was more likely to be less than WHO reference values in never-users than current and past-users,” the study abstract notes.

Specifically, that was the case for 38.3 per cent of never-users compared to 21.1 per cent of current users and 27.2 per cent of past users.

“Large, prospective studies of both semen quality and fertility in this growing, at-risk population are warranted,” the investigators conclude.

To date, research on weed’s influence on sperm quality runs the gamut. IFL Science reports research out of Denmark found regular cannabis consumption was associated with a 30 per cent drop in sperm count, while a U.S. study determined weed users tended to have a higher sperm count than never-users.