Payne, K. S., Mazur, D. J., Hotaling, J. M., & Pastuszak, A. W. (2019). Cannabis and Male Fertility: A Systematic Review. The Journal of urology, 202(4), 674-681. https://doi.org/10.1097/JU.0000000000000248
Payne KS, Mazur DJ, Hotaling JM, Pastuszak AW. Cannabis and Male Fertility: A Systematic Review. The Journal of urology. 2019;202(4):674-681. doi:10.1097/JU.0000000000000248
Payne, Kelly S., et al. "Cannabis and Male Fertility: A Systematic Review." The Journal of urology, vol. 202, no. 4, 2019, pp. 674-681.
Cannabis use is linked to lower sperm count and quality in men
Cannabis use is linked to lower sperm counts and poorer sperm quality in men, a 2019 review of 48 animal and human studies reports. Most evidence comes from animals and lab tests. Studies in men disagree on testosterone, and testicular shrinkage has been reported only in animal studies.
Key Findings
In a Danish cohort of 1,215 men, marijuana users above once a week showed lower sperm concentration and lower sperm count than men with no history of use.
Among 1,700 men at 14 UK fertility clinics, men under 30 who used cannabis in the prior 3 months were more likely to have abnormal sperm shape (OR 1.94, 95% CI 1.05–3.60).
Laboratory and animal work reported reduced sperm motility, signs of lower viability and reduced fertilizing capacity. Motility has the most extensive body of evidence.
Testosterone findings conflict: higher in Danish marijuana smokers, no difference between ever and non-users among 1,577 US men. LH was lowered in most studies and FSH showed no effect in most.
Animal experiments produced testicular atrophy and reduced libido. The review notes human studies have not yet repeated these results.
Interpretation
The authors searched PubMed up to May 2018 and reviewed animal work, lab tests on sperm and retrospective analyses of men. Most evidence comes from animals and lab dishes, so the human findings show association and possible mechanisms. Ethical and legal barriers limit controlled human studies. The Danish authors could not separate testosterone effects from tobacco smoking. The review names no level of use that lowers fertility and leaves open whether effects reverse in men.
RRM Context
Restorative reproductive medicine looks for causes in both partners. Male factor contributes to infertility in many couples. Exposures that affect sperm belong in that search. The review itself suggests clinicians weigh how much a man uses cannabis when they evaluate male infertility.
Our editorial summary of this paper, not the article's abstract.
Abstract
Purpose
With cannabis consumption on the rise and use prominent among males of reproductive age it is essential to understand the potential impact of cannabis on male fertility. We reviewed the literature regarding the effects of cannabis on male fertility.
Materials and Methods
We performed a literature search using PubMed®/MEDLINE® to identify relevant studies of the effects of cannabis on male fertility. Relevant studies were identified and reviewed.
Results
The strongest evidence of cannabis induced alterations in male fertility is in the category of semen parameters. Research supports a role for cannabis in reducing sperm count and concentration, inducing abnormalities in sperm morphology, reducing sperm motility and viability, and inhibiting capacitation and fertilizing capacity. Animal models demonstrate a role for cannabis in testicular atrophy, and reduced libido and sexual function but to our knowledge these results have not yet been replicated in human studies. Studies of hormonal changes suggest inconclusive effects on testosterone levels, lowered luteinizing hormone levels and unchanged follicle-stimulating hormone levels.
Conclusions
Current research suggests that cannabis may negatively impact male fertility. Further studies are needed to validate that robust findings in animal models will carry over into human experience. Clinicians should be aware of these potential effects when prescribing medical marijuana therapies to men of reproductive age, and they should consider the degree of cannabis use as a possible component of a complete male infertility workup.
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