While this can complicate a finite answer, doctors do believe more research needs to be done.
"There are many lab studies showing negative effects of marijuana on sperm. There are surprisingly few human trials, but they all demonstrate that cannabis use reduces sperm concentration, sperm motility (ability to swim), or both," says Doron Stember, MD, assistant professor of urology at the Icahn School at Mount Sinai.
If the evidence seems stacked against marijuana use, there have also been some studies that negate marijuana's negative effects on fertility.
But if you do smoke marijuana and have difficulty conceiving, it may not be the sole root cause of your infertility issues.
And a 2019 study published in the journal Human Reproduction found that men who reported using cannabis had "significantly higher" sperm counts than men who reported never using cannabis.
Besides the impact on sperm count and mobility, it was also found to fundamentally change the sperm itself.
"Tetrahydrocannabinol (THC), the active compound of marijuana, binds to receptors in many different glands and tissues that are involved in sperm production," says Matthias Hofer, MD, urologist at Northwestern Memorial Hospital. "These receptors are found in the hypothalamus and pituitary gland, decreasing hormone production necessary for sperm production."
“However, for couples with infertility, the changes in ovulatory function and sperm count associated with smoking marijuana could compound their difficulty with conceiving,” they wrote.
As U.S. states, including Alaska and Colorado, and countries, including Canada, legalize marijuana, scientists are working to understand the threat this could pose to users’ health.
Asked if there is a risk that as cannabis is decriminalized and legalized people will see it as safe and be less wary of the potential harms, Ian Hamilton of the Department of Health Sciences at the University of York recently told Newsweek: “There is a potential risk that these policy changes are perceived by young people and adults as signalling that cannabis is harmless.”
Other recent studies have also highlighted the potential health risks associated with using the drug. A study published in April found that people who regularly use cannabis need a 220 percent higher dose of sedatives during medical procedures.
Using weed is thought to reduce sperm count, for instance. One study involving 1,215 men found that 130 individuals who smoked marijuana more than once a week in the past three months saw a cut in production of the total sperm count of 29 percent. But the cells were still able to swim and were the same size and shape in this study.