There’s been a notable increase in cannabis users—both for medical purposes and recreationally—all over the world in the past 30 years. As a result, a lot more questions have been raised regarding how cannabis affects the human body in different ways.
Lots of scientific research has been conducted, but we still have a long way to go before truly understanding the myriad ways that cannabis can affect our different systems—in particular, the human reproductive system.
Scientists have conducted some experiments on this topic and have made some interesting discoveries, but research on the topic of cannabis and reproductive health is still largely lacking. Here is what we currently know about how cannabis affects the reproductive system and fertility among both men and women.
How the Endocannabinoid System & Reproductive System Work Together
The endocannabinoid system is a network of receptors that exists throughout the human body. It helps regulate and communicate with the brain, immune system, and endocrine tissues.
Among serving many different purposes within our bodies, the endocannabinoid system plays an important and complex role in the secretion of hormones related to reproductive functions in particular.
When people ingest cannabis, cannabinoids such as THC and CBD act on the endocannabinoid receptors in our body. The endocannabinoid system is thus affected, which in turn causes a wide array of biological effects as a result—including on the reproductive system.
Both men and women can experience changes to their reproductive systems when they consume cannabis regularly, as the secretion of hormones becomes altered. As such, changes in fertility regulation may occur.
Male Reproductive Health & Cannabis
Many people have asked, does marijuana affect sperm? Here’s what the research says.
A four-year study of more than 1,200 men that was conducted in Denmark and published in 2015 does suggest that regular consumption of cannabis could result in lower sperm concentration. The study found that men who reported smoking more than once per week had a 29% lower total sperm count compared to the men that reported not smoking cannabis.
However, there’s actually other scientific research that found the opposite to be true. A team from the Harvard T. H. Chan School of Public Health, which published a new study in 2019 on the subject, was surprised by its unexpected findings on the effects that smoking cannabis has on markers of male fertility.
The research team originally hypothesized that men that consume cannabis would have poor sperm quality. However, that is not the conclusion their study reached.
The team recruited 662 men in Massachusetts between 2000 and 2017 and analyzed 1,143 semen samples from study participants. They also used blood samples to test for reproductive hormones.
The researchers found the cannabis users had an average sperm concentration of 62.7 million sperm per milliliter, while those who never used cannabis had an average of 45.4 million sperm per milliliter. They also observed that only 5% of cannabis users had sperm concentrations that are considered below normal, while 12% of non-cannabis users had below-normal sperm concentrations.
“[The] unexpected findings highlight how little we know about the reproductive health effects of marijuana and, in fact, of the health effects of marijuana in general,” study author Jorge Chavarro wrote. “Our results need to be interpreted with caution, and they highlight the need to further study the health effects of marijuana use.”
Clearly, more scientific research is required for us to truly understand how cannabis use affects male fertility.
Female Reproductive Health & Cannabis
Very few studies have examined the relationship between female reproductive health and cannabis use. It’s more difficult to study the effects of cannabis on the female reproductive system because there is no direct measure to examine, as men have with semen.
The mechanisms by which cannabis may disrupt the female reproductive system involves the hypothalamic-pituitary-ovarian (HPO) axis, which helps to regulate female reproduction.
The little scientific evidence that is out there suggests that cannabis has the potential to reduce female fertility by disrupting the production of estrogen and progesterone hormones. This disruption can delay the ovulation cycle, or possibly even prevent ovulation from occurring at all. In the case that ovulation does not occur—which is known as an “anovulatory cycle”—no egg will be released and thus pregnancy cannot occur.
That said, some studies have found no effect at all on the ovulation and menstrual cycle in women who use cannabis, making it even clearer that more scientific research is required on this subject.
Similarly, the health effects of using cannabis during pregnancy are also not yet well understood.
Cannabis use has been rapidly rising among pregnant women where medical and recreational laws have been passed. In a study conducted in California, it was found that the percentage of pregnant women who screened positive for cannabis use nearly doubled between 2009 and 2016 — jumping from 4% to 7% over the seven-year period.
We do know that THC can cross the placenta and reach the fetus, and it can also be secreted in breast milk for up to six days after the last use. This leads to concerns about the effects of using cannabis during pregnancy and breastfeeding, as it exposes the fetus/newborn to the drug.
Yet, a study conducted in England on pregnant women who used cannabis found that cannabis use did not result in an increased risk of perinatal morbidity or mortality. However, the study did conclude that frequent and regular use of cannabis throughout pregnancy could be associated with a small but statistically detectable decrease in birth weight.
In conclusion, it is clear that much scientific research still needs to be conducted on how cannabis use affects both male and female reproductive systems.
According to the research above, couples with pre-existing fertility issues trying to have a baby may find that using cannabis could potentially exacerbate the difficulties of getting pregnant.
That said, some evidence does suggest that couples without fertility issues should not experience any major issues from using cannabis when trying to conceive.
As always, it is important to discuss with a medical professional should you have any questions or concerns about cannabis use and your reproductive health.