Interesting, if not conflicting, research has recently been published on the topic of marijuana and infertility. Here, our experts take a closer look. Research indicates the use of cannabis may affect human fertility, depending on gender, general health, socioeconomic status and several other factors. Learn about whether marijuana can cause infertility, including a review of research on marijuana's effects on women and men.
Marijuana and Infertility: What You Need to Know
All information on this website is for general informational purposes only and is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment.
For decades, there has been an ongoing discussion regarding cannabis and infertility. Numerous anecdotal outlets have cited decreased fertility rates among cannabis users (especially a decline in sperm count in males), but is there any clinical or scientific evidence to back up these claims?
In this article, we discuss relevant contemporary research relating to the topic. We’ll also discuss whether “marijuana infertility” is truly a concern. Read on to find out more.
Does Marijuana Cause Infertility?
There is a body of evidence suggesting that marijuana causes infertility. However, even more concerning is relatively recent research that suggests that fertility, especially in males — may be declining overall.
A study published in Human Reproductive Update in 2017 identified a potentially key issue. It looked at 7,500 studies performed from 1973 to 2011. The researchers found that men from Australia, New Zealand, Europe, and North America had an almost 60% decline in sperm count. They also had a sperm concentration decline of 52%.
Researchers offered several hypotheses attributed to the decline in semen quality. These include:
- Increase exposure to pesticides
- Meta-changes in diet
- Exposure to higher-temperature climates
- Meta-changes in Body Mass Index (BMI)
- Other lifestyle/environmental factors
A major underlying concern, particularly given evidence that cannabis use is on the rise (as well as evidence that smoking tobacco affects fertility), is whether or not marijuana causes infertility. Another is whether cannabis use may have a variable impact on males’ and females’ fertility and reproduction potential.
Potential Impact of Cannabis Use on Female Fertility
Data regarding the relationship between female infertility and marijuana use is limited. However, a study published in the Journal of Women’s Health in 2016 suggests that smoking cannabis can delay a woman’s ovulation by several days.
Furthermore, a separate study published by the National Institute on Drug Abuse suggests that cannabinoids can alter hormone secretion related to reproductive function. Authors suggest that cannabinoids, specifically THC, can “inhibit secretion of LH, FSH, [and] prolactin,” resulting in “decreases in sex steroid hormones [as well as] changes in ovulation.”
However, the researchers observed that these effects are reversible when cannabis use is ceased.
Still, most experts recommend that pregnant women and women who are considering becoming pregnant – avoid the use of cannabis altogether both during and before pregnancy. This recommendation is more pressing than ever, as cannabis use among young reproductive-aged women is rising.
In fact, according to currently available statistics, upwards of 8% of non-pregnant reproductive-aged women use cannabis on a relatively consistent basis. As authors of the above publication observe, “prenatal marijuana exposure [can be] associated with poor offspring outcomes,” including an increased prevalence of conditions like low birth weight and impaired brain development.
What About Male Fertility? Does Cannabis Reduce Sperm Count?
Another pressing concern – and an ongoing topic of debate circulating for decades – is whether or not marijuana can cause male infertility.
A study published in the American Journal of Epidemiology in 2015 appears to suggest that it can. The study observed over 1,200 Danish men aged 18-28, 45% of which had smoked cannabis in the previous three months. Twenty-eight percent of study participants used marijuana more than once a week. The study discovered that those who used cannabis regularly had a 29% reduction in sperm count.
The answer may shock you!…
However, a study published in Human Reproduction in 2019 appears to contradict the research above. This study, which took place over 17 years from 2000 to 2017, examined 1,100 semen samples from male patients enrolled in the Massachusetts General Hospital Fertility Center. The study found that cannabis users had a higher sperm count per milliliter of ejaculate (62.7 million sperm compared to 45.4 million in non-cannabis users). Only 5% of cannabis-using test subjects had sperm count levels considered low (below 15 million per milliliter).
Based on the availability of contemporary research data, the impact of cannabis use on male fertility is still largely inconclusive.
Additional Research on Weed and Infertility
Another interesting publication on the broader topic of weed and infertility appeared in 2018 in the peer-reviewed academic journal Fertility and Sterility.
In the study, researchers analyzed nearly 2,000 male and female participants that were trying to conceive. Eleven-and-a-half percent of women admitted to using cannabis during this period, along with 16.5% of men. The study results suggested that cannabis use did not have a negative impact on the time it took for couples to become pregnant.
Again, however, it is highly recommended that cannabis use be avoided among individuals trying to conceive.
Bottom Line on Marijuana and Infertility
The general discrepancy in the observations made from these above-referenced studies means we can’t draw any firm conclusions regarding the ongoing debate of marijuana and infertility. Without a doubt, more research needs to be done on the topic.
Unfortunately, there are still challenges associated with carrying out quality cannabis-based research.
At present, cannabis is only fully legal (on a national level) in Canada and Uruguay. This means that federal research funding for cannabis studies is still difficult for many global research organizations.
Regardless of whether or not marijuana causes infertility, it is best to avoid the consumption of cannabis altogether for those trying to conceive. Likewise, pregnant women should always steer clear of any form of cannabis use.
Effects of Cannabis on the Male and Female Reproductive System, and Fertility
Use of cannabis may affect human fertility, depending on gender, general health, socioeconomic status and several other factors. Here, we look at existing research on cannabis and human fertility, in order to provide readers with an accurate, up-to-date summary of the current state of scientific knowledge.
To understand how cannabis may affect fertility, we must understand the effect it has specifically on males and on females. We’ll start by looking at the effects on the male reproductive system, and then focus on the more complicated effects on female fertility.
Cannabis use and male fertility
Some studies on the effect of cannabis use on male fertility have indicated that regular use may reduce spermatogenesis (the production of sperm in the testes) and testosterone levels.
In 2012, the American Society of Andrology published a review of research on the effects of illicit drug use on male fertility. The researchers found that in the majority of studies, it was consistently concluded that cannabis use had a negative impact on male reproductive physiology.
Another study in 1992 (Vescovi et al.) found that levels of luteinizing hormone(LH), an important pituitary gland hormone involved in reproductive function, were reduced in male chronic cannabis users compared to a non-cannabis-using, age-matched control group. A previous 1986 study (Cone et al.) also found a significant reduction in LH levels immediately after smoking cannabis.
And an even earlier study (Kolodny et al, 1974) into testosterone levels in “chronic” cannabis users found that 6 of 17 subjects had oligospermia (low sperm count), and that average testosterone levels in the cannabis-using group were just over half that of the control group. The effect of cannabis on testosterone levels was observed to be dose-dependent.
Sexing Cannabis: Is My Plant Male or Female?
The endocannabinoid system and male fertility
Clearly, the endocannabinoid system has a role to play in the regulation of processes critical to male reproductive health, such as sperm count, testosterone levels, and levels of other key hormones such as LH.
For healthy adult males, it seems that use of THC does indeed cause some negative effects on fertility, which tend to increase with higher doses. However, THC’s endogenous analogue anandamide appears to be critical to the functioning of the male reproductive system.
The 2002 study found that sperm cells would bind to the agonist CP-55,940, demonstrating the presence of CB1-receptors. The study also concluded that the presence of THC and a synthetic anandamide analogue, AM-356, both reduced sperm motility in vitro. Interestingly, it was found that AM-356 exerted a biphasic dose-dependent effect on sperm motility, causing inhibition at high doses but hyperactivity at low doses.
Anandamide and the “capacitation” of human sperm cells
In a 1994 study, it was found that mammalian sperm, including that of humans, is actually incapable of fertilizing oocytes (eggs) immediately after leaving the testes. It requires a period of exposure to certain crucial hormones, enzymes and proteins on its journey through the vas deferens and ejaculatory ducts of the male reproductive system (as well as the reproductive fluids of the female vagina and oviducts) before becoming “capacitated” and able to fertilize an egg.
The 2002 study provides strong evidence that the presence of the anandamide in the seminal fluid, and its ability to bind to the CB1-receptors of the spermatozoa, are key to the “capacitation” of sperm cells on their way to the ejaculatory ducts. It has to be present in the appropriate concentrations, though. If the level of anandamide is too high, it can instead have a dramatic inhibitory effect on the sperm cells’ ability to fertilize oocytes.
How Does Cannabis Affect the Digestive System?
Why is anandamide beneficial, while THC may not be?
Although THC and anandamide are both agonists of the CB1-receptors, they greatly differ in structure and therefore have different effects on certain metabolic processes. Anandamide has a much shorter half-life than THC (just a few minutes for anandamide compared to as long as 24 hours for THC). So while anandamide will degrade shortly after it contacts a receptor, THC can remain in nearby adipose tissue for much longer periods, and can continue to stimulate the receptors, ultimately causing overstimulation and potential negative effects.
As is so often the case with cannabinoid science, dosage is everything—and it may prove to be the case that very small doses of THC could benefit males who have reproductive issues that can be tied to low levels of anandamide.
Cannabis use and female fertility
While the effect of cannabis use on male fertility appears to be quite straightforward—with male chronic cannabis users being likely to experience some degree of impairment to reproductive physiology—the effect on the human female reproductive system is less clear-cut.
Female reproductive health is vastly complex in itself, as it not only comprises the ability to become pregnant but also the ability to carry healthy offspring to term and successfully give birth.
Past research has indicated that cannabis use may disrupt the menstrual cycle, suppress oogenesis (production of eggs in the ovaries) and impair embryo implantation and development. Chronic use of cannabis has also been repeatedly associated with lower birth weight (as much as a 50% increased risk), decreased birth weight and early (spontaneous) termination of pregnancy.
However, most of these findings are far from conclusive. Either the study included very few participants or confounding factors such as tobacco use aren’t taken into consideration. In fact, more recent research, like this review on infants who were exposed to marijuana in-utero, concludes there aren’t any adverse risks.
For example, a 1985 paper on foetal abnormality (Qazi et al.) after prenatal exposure to cannabis discussed five infants whose mothers acknowledged use of cannabis prior to and during pregnancy and who were born with various symptoms of growth retardation, neurological dysfunction and deformity. While it may provide helpful insight, such a small sample size is far from being enough to draw concrete conclusions, and correlation does not imply causation.
Other studies seen as providing evidence that cannabis use can cause foetal abnormalities are animal studies (Geber & Schramm 1969, Phillipset al, 1971) in which rabbits, hamsters, rats and mice were injected with vast doses of crude cannabis extract (as much as 666mg/kg in one instance!). Such massive doses of cannabis would be practically impossible for a human to consume through conventional means, and are essentially useless as a point of comparison.
In fact, many early studies that indicated a correlation between use of cannabis (or other controlled substances such as cocaine) have been later contradicted by findings suggesting that socioeconomic status and level of poverty are far more causative of low birth weight and poor developmental outcome than use of the substances themselves. This doesn’t imply that use of cannabis or other substances during pregnancy has no adverse effect, but does give weight to the idea that the risks have been overestimated and overemphasized due to politics and anti-drug bias.
How Marijuana Can Affect Fertility
Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada.
Verywell Mind articles are reviewed by board-certified physicians and mental healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more.
Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital.
Although the link between marijuana and fertility is not straightforward—plenty of marijuana smokers get pregnant and get their partners pregnant—some research has demonstrated that marijuana use can negatively impact you, your partner, or the fertility of both of you.
Research suggests that marijuana can negatively affect female fertility in the following ways:
- Decreases libido. Even before intercourse takes place, marijuana use may decreases libido. And if you aren’t feeling in the mood, it’s that much more difficult to get started.
- Increases the risk of miscarriage. Marijuana use also increases the risk of miscarriage. Marijuana is known to cross the placenta and may pose a risk to the fetus, although the effects of marijuana exposure in the womb are not as well documented as the effects of alcohol and some other drugs.
Furthermore, the effects of marijuana on fertility seem to accumulate over time. This means that although teenage girls who smoke marijuana are more likely to get pregnant, by the time a chronic marijuana smoking woman is in her mid-twenties, she may be more likely to experience a delay in getting pregnant.
Despite the relaxation effects that many people associate with marijuana use, research has shown marijuana has negative effects on the male sexual response.
- Increases impotence. Cannabis use has been associated with sexual dysfunction, which can also have negative effects on the male ego. If your partner has been impotent, he may be feeling more pressure to have sex to get you pregnant, but be frustrated with his inability to do so. This can lead to misunderstandings between you that make it more difficult to have sex.
- May lead to premature ejaculation. Marijuana use has been associated with premature ejaculation.
- May decrease sperm count. A regular smoker of marijuana has a risk of having a lower sperm count.
- Affects sperm structure and function. Additionally, the sperm produced by marijuana smoking has been associated with abnormal morphology (shape) and motility (its ability to “swim” and fertilize the egg).
Quit to Prepare for Parenthood
Obviously, if you are both smoking marijuana, you risk increasing the chances of infertility as a couple.
Quitting marijuana can be harder than many long-term marijuana users expect, so you and your partner would be wise to quit as soon as possible, while you still have time to get help before getting pregnant. If either or both parents still use marijuana when the baby arrives, you are increasing the risk that your child may use drugs in the future, and parental drug use is implicated in many difficulties for children and families.
Your family doctor can help you with a referral to a counselor or clinic that can help you both quit. Couples counseling, which is offered by many addiction clinics, would be particularly helpful at this time. If you are already engaged in infertility treatment, coming clean about your marijuana could save you a lot of time, money, and heartache, if marijuana is one of the culprits for your difficulties with conception.
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Bari M, Battista N, Pirazzi V, Maccarrone M. The manifold actions of endocannabinoids on female and male reproductive events. Front Biosci (Landmark Ed). 2011;16:498-516. doi:10.2741/3701
By Elizabeth Hartney, BSc, MSc, MA, PhD
Elizabeth Hartney, BSc, MSc, MA, PhD is a psychologist, professor, and Director of the Centre for Health Leadership and Research at Royal Roads University, Canada.