A bunch of scientists gathered sperm counts from 662 men who visited a fertility clinic with their significant other and they were shocked to find that participants who took marijuana at some point in their life have higher sperm count than others.
The interesting bit comes when their past and present drug use was taken into account, with 55% of those surveyed noted that they had smoked marijuana at some point during their lives, while 11% identified as current smokers. This system sends signals to the brain and these signals may play a role in fertility, they explain.
"An equally plausible interpretation is that our findings could reflect the fact that men with higher testosterone levels are more likely to engage in risk-seeking behaviours, including smoking marijuana".
And rightfully so. In 2015, a study published in the American Journal of Epidemiology examined 1,215 healthy young men and found that those who used recreational marijuana a few times per week had lower sperm counts than those who used the substance less often or not at all.
One possible explanation could be that men who generally produce higher testosterone levels are more likely to use marijuana, rather than the implication that cannabis use itself affects sperm potency.
"These unexpected findings highlight how little we know about the reproductive health effects of marijuana, and in fact of the health effects of marijuana in general", said Jorge Chavarro, associate professor of nutrition and epidemiology at Harvard Chan School.
However, Chavarro noted that some of those past studies surveyed men who use multiple drugs at once, making it hard to pinpoint the effects of marijuana alone.More news: Haas launches new look for 2019 Formula One season
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Previous studies had suggested that smoking marijuana may lower a man's sperm count, especially among heavy users.
The researchers then compared each man's semen and hormone analysis to his reported marijuana use.
However, the new experiment, published Feb.6 in the issue of Journal Human Reproduction, does not urge men to start smoking the plant to up their sperm count. The majority of the men participating had normal sperm counts, suggesting that other conception issues may have been the issue.
"What this study shows is pot smoking doesn't make you automatically infertile, but there have been studies on pot smoking for many years and there are a good number of studies out there that indeed have reported adverse effects on semen in pot smokers", Gleicher said.
Nassan also said that the results may have been skewed by cannabis prohibition.
None of these limitations or considerations invalidate study's findings, it's just a sign, as Chavarro said, that we need to study cannabis more (the fact that cannabis is still considered more unsafe than opioids by the USA government remains a roadblock to that research, incidentally).
It is estimated that 16.5% of adults in the USA use marijuana, and support for legal recreational use of marijuana has increased dramatically in recent years.
Fifty-five percent of the men said they'd smoked pot at some point, with 44 percent saying they were past smokers and 11 percent reporting they now toke.
With these limitations in mind, it is clear more research must be done to truly understand how marijuana use can affect a person's sperm and, by default, their fertility.