In April 2019 researchers from the USA published the results of their study to assess the effect of marijuana smoking on semen quality, sperm DNA integrity and reproductive hormone levels in subfertile men. A total of 662 subfertile men were included in the study. The men provided a total of 1143 semen samples whilst 317 men also provided blood samples for the assessment of reproductive hormones. Information on the use of marijuana and other drugs was self-reported, and showed that 365 men had smoked marijuana at least once with 74 being current marijuana smokers and 291 past smokers. It was noted that 297 men had never smoked marijuana. Results showed that men who had smoked marijuana at least once had a significantly higher sperm concentration and sperm count than men who had never smoked marijuana. The number of individuals who had a sperm concentration and total sperm motility below the WHO reference values was twice as high in the group who had never smoked marijauna. Those who had never smoked marijuana smokers also had significantly higher levels of FSH than those who had never smoked marijuana. No significant differences in sperm concentration, sperm count and FSH levels was seen between current and past marijuana smokers. Marijuana smoking was not associated with other semen parameters. However, the researchers advised caution in their findings as their results may not be reproducible in a the wider population as marijuana smoking was self-reported and there may be a misclassification of the exposure.
Nassan FL et al. Marijuana smoking and markers of testicular function among men from a fertility centre. Hum Reprod. 2019 Apr 1;34(4):715-723