The small study, which looked at the sperm of 37 men who either used or did not use dagga, concluded that use of the substance can significantly change a person's sperm concentration. The study also looked at how cannabis use affected ejaculation, semen volume, semen pH, and motility, and found that the substance did not create a significant change in these categories.
"What we have found is that the effects of cannabis use on males and their reproductive health are not completely null, in that there's something about cannabis use that affects the genetic profile in sperm," Scott Kollins, a senior author of the study, said in a statement.
Sperm concentration, along with other factors like sperm motility and testosterone levels, can affect a person's ability to conceive a child, according to the Mayo Clinic. So the study's findings suggest a person who uses cannabis may have more difficulty conceiving than someone who does not use cannabis.
This factor is important because if fewer sperm are present in a person's semen, there is a decreased chance that a sperm will reach an egg and fertilise it. According to the Mayo Clinic, a low sperm count or concentration means a person has fewer than 15 million sperm per millilitre of semen. To determine a person's sperm count, doctors must look at semen under a microscope on two separate occasions for accuracy purposes, the Mayo Clinic explained.
Since sperm concentration can greatly affect a person's reproductive abilities, the study's authors also looked at the potential for this trait to be passed from a cannabis user down to their offspring. Based on previous studies about cigarette smokers' ability to pass on certain traits, they found that there is a chance cannabis users who have genetically-changed sperm might cause their children to also have genetically changed sperm.
Since the sample size of the study was relatively small, however, more research must be done to understand how cannabis affects a person's sperm and how those genetic-level changes could be passed down to offspring.
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