Marijuana May Cause Decreased Sperm Counts, New Study Finds

By Michael Roberts

While medical marijuana patients talk up the health benefits of MMJ, anti-pot activists insist that cannabis actually impairs brain function, among other things.
For a laundry list of why marijuana is bad for you, see this Colorado Department of Public Health and Environment report from earlier this year.
Turns out, however, that the latest negative health report about pot — claims that marijuana does bad things to sperm — isn't exactly new.

The spur for the new claims is "Association Between Use of Marijuana and Male Reproductive Hormones and Semen Quality: A Study Among 1,215 Healthy Young Men," published in the American Journal of Epidemiology. The following abstract summarizes the findings:

A total of 1,215 young Danish men aged 18–28 years were recruited between 2008 and 2012 when they attended a compulsory medical examination to determine their fitness for military service. The participants delivered a semen sample, had a blood sample drawn, and underwent a physical examination. They responded to questionnaires including information on marijuana and recreational drug use during the past 3 months (no use, use once per week or less, or use more than once per week). A total of 45% had smoked marijuana within the last 3 months. 

Regular marijuana smoking more than once per week was associated with a 28% (95% confidence interval (CI): ?48, ?1) lower sperm concentration and a 29% (95% CI: ?46, ?1) lower total sperm count after adjustment for confounders. The combined use of marijuana more than once per week and other recreational drugs reduced the sperm concentration by 52% (95% CI: ?68, ?27) and total sperm count by 55% (95% CI: ?71, ?31). Marijuana smokers had higher levels of testosterone within the same range as cigarette smokers. Our findings are of public interest as marijuana use is common and may be contributing to recent reports of poor semen quality.

A piece in Live Science notes that the results can't be considered definitive.
The authors of the study concede that "we cannot exclude the possibility that the men who used marijuana generally have an unhealthier lifestyle and health behavior, which may also affect their semen quality and hormone levels."
Be that as it may, previous studies have also found a correlation between sperm-related issues and marijuana. In 2014, for instance, a piece in the journal Human Reproduction noted that cannabis may affect sperm's size and shape, and a 2004 analysis originally shared in The Journal of Clinical Endocrinology & Metabolism states that "cannabinoids and endocannabinoids negatively influence sperm functions," including motility.

File illustration

There's an upside to the situation, however, as pointed out two years ago by our Ask a Stoner columnist in a piece with the headline, "Will Smoking Pot Kill My Sperm?" To whit: The effects of pot smoking on sperm may be reversed simply by quitting for a while — much as women who are pregnant lay off alcohol. Here's the question and answer from the previous Ask a Stoner piece:

Dear Stoner: The wife and I are trying to get pregnant, and she's insisting that pot is killing my little swimmers. It sounds like pot paranoia to me. But is she right? Should I stop smoking for a while? — C. Mann Dear C: While there are a few studies to the contrary, most physicians and research shows that marijuana use does have some effect on your tadpoles — particularly in their shape, how straight they swim and how well they release hormones that allow them to break into an egg. So, yes: Laying off the herb isn't a bad idea if you're trying to increase your odds of having a kid.
The good news is that any damage you may have done up to this point is probably reversible within sixty to ninety days. And let's face it: Those stats haven't stopped stoners throughout history from having plenty of kids. If Willie Nelson can father seven children, you've got good odds.
That said, my advice is to do what your wife wants. If you haven't figured out by now that you aren't happy unless your wife is happy, this may be a good learning opportunity.

We imagine this last comment is likely to inspire an "Amen" or two.