Is Pot Hurting Your Sperm?
If the birth rate in Colorado drops off next year, there may be a new obvious reason: Smoking pot could be linked to sperm changes that may make it harder to get her pregnant, says new research in Human Reproduction.
The study involved nearly 2,000 U.K. men who had given sperm to one of 14 fertility clinics. The guys filled out surveys about their lives—alcohol use, tobacco use, and other vices—and gave researchers the go-ahead to test out their swimmers in a lab.
The results: Guys age 30 and younger who reported using marijuana at least once in the past three months had nearly twice the odds of poor sperm morphology, which refers to the size and shape of sperm. Only sperm with a normal size and shape are able to navigate the gauntlet of barriers that get in the way of fertilizing an egg, experts say. The study didn’t ask about how often the men used marijuana or how much they used. So it’s impossible to know if just a little bit of marijuana may affect semen, or if the use has to be excessive.
So why might weed mess up the fertility of your sperm? “We have no hypothesis. However, there is work from mice suggesting that cannabis can change the way that DNA is packaged, and this could indirectly lead to changes in sperm size and shape,” says lead author Allan Pacey, Ph.D., of the University of Sheffield in England.
Samples taken in the summer months were also more likely to have poor sperm size and shape, though the researchers don’t know why. And unlike those who admitted to pot use, other negative health factors like alcohol, tobacco, street drug use, and body mass index weren’t linked to sperm changes.
“Men who want to have children should make sure they are as healthy as possible and have regular sex with their partner,” Dr. Pacey says. Although this study didn’t find much of an effect of lifestyle on sperm size and shape in general, other research shows that you can take steps to improve your semen's strength. If you want to be a dad—now or later—follow our 7 Tips for Strengthening Your Swimmers.