Marijuana smoking makes sperm less fertile — even if the woman is the one who smokes it, a new study suggests. Interesting, if not conflicting, research has recently been published on the topic of marijuana and infertility. Here, our experts take a closer look. Some recent studies suggest that marijuana can negatively affect fertility in both men and women. Read the article to learn about the correlation between marijuana and fertility to get informed about the latest findings.
Smoking Marijuana Lowers Fertility
Oct. 13, 2003 — Smoking marijuana makes sperm less fertile — even if the woman is the one who smokes it, a new study shows.
Marijuana-smoking college men volunteered for the study led by Lani J. Burkman, PhD, director of andrology at the University of Buffalo School of Medicine and Biomedical Sciences.
The smokers weren’t the only ones who got high. The drug affected their sperm, too. These stoned sperm party hard. And then? They burn out, researchers say.
“Marijuana-smoking men’s sperm are hyper. They are way out there,” Burkman tells WebMD. “They already have begun the vigorous swimming called hyperactivation. Sperm should be quiet at first. They should be waiting to be washed into cervix and approach the egg before they start hyperactivation.”
So the little guys are fast out of the gate, right? What’s wrong with a little head start?
“It is not a head start. They are going to blow it,” Burkman says. “They’re too fast, too early. Each individual sperm can maintain this swimming only so long, only several hours. Then it poops out. If it has run out of hyperactivation before it gets close to the egg, it will not fertilize. These sperm are going to burn out.”
Burkman announced the findings at this week’s meeting of the American Society of Reproductive Medicine.
Marijuana and Fertility Timing
When it comes to romance, timing is everything. That holds true for fertility, too, says Celia E. Dominguez, MD, of the Center for Reproductive Medicine at Emory University, Atlanta.
“The reason men have millions of sperm is because the fertility process is more difficult than people think,” Dominguez tells WebMD. “The whole process of ascending up the tract to the fallopian tubes and then finding the egg is delicately balanced.”
As the sperm approaches the egg, it receives a signal to start swimming — hard. This hyperactivation lets it push through the egg cover. Pooped out sperm don’t have a chance. Learn about more ways marijuana can affect fertility.
Of course, men who smoke marijuana do get women pregnant. But some men are more fertile than others, or are more fertile at different times of their lives. Smoking marijuana, Burkman warns, will make a borderline-infertile man frankly infertile.
“The marijuana-smoking men had significantly lower semen volume,” Burkman says. “Many had pretty low volume, about half the male norm. If they came to our clinic as patients, we’d tell them they are abnormal. . They are delivering significantly fewer sperm to the female when they have sexual intercourse.”
Burkman’s team studied only men. But she says that when women smoke marijuana, the active ingredient — THC — appears in their reproductive organs and vaginal fluids. Sperm exposed to this THC are likely to act just as sperm exposed to THC in the testes.
“When women smoke marijuana, nicotine, or other drugs, their reproductive fluids contain these drugs,” Burkman says. “The woman smoking marijuana is putting THC into her oviduct, into her cervix. If the man is not smoking but the woman is, his sperm go into her body and hit THC in the vagina, oviduct, and uterus. Her THC is changing his sperm.”
Dominguez says that Burkman’s study is more important than merely warning men and women to avoid marijuana if they want to get pregnant. She says that by learning how the reproductive tracts of men and women respond to different chemical signals, researchers will learn more about how to help people get pregnant — or even to avoid it.
SOURCES: Burkman, L.J. “Marijuana Impacts Sperm function both In Vivo and In Vitro: Semen analyses from Men Smoking Marijuana,” Conference, American Society of Reproductive Medicine, San Antonio, Texas, Oct. 11-15, 2003. Lani J. Burkman, PhD, director, andrology department, University of Buffalo School of Medicine and Biomedical Sciences, Buffalo, N.Y. Celia E. Dominguez, MD, Center for Reproductive Medicine, Emory University, Atlanta.
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.
Three Ways Marijuana Can Affect Fertility
Some studies show that marijuana use negatively affects fertility in men and women. Many articles and physicians advise against using marijuana while trying to get pregnant to reduce the risks of infertility. Learn more about the warnings signs of infertility and discover how you can develop healthy habits to increase your chances of getting pregnant.
Anna Klepchukova, MD
1. Ovulation delay
Scientists aren’t sure exactly how THC affects the sexual function of women attempting to get pregnant. THC affects the hypothalamic-pituitary-gonadal (HPG) axis, which controls how your sex hormones interact. Continuous exposure to THC can inhibit the secretion of luteinizing hormone and prolactin from the pituitary gland in males and females. These hormones influence your chances of getting pregnant.
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In women, high THC doses interfere with the menstrual cycle and may delay or prevent ovulation. Cannabinoids inhibit the activity of the HPG axis, meaning that marijuana use decreases the production of several hormones and can inhibit sexual behavior — if your sex drive is down, this can also hinder your efforts to conceive.
Regular smokers may have an elevated risk of not ovulating at all. A 2016 report also suggests marijuana disrupts the menstrual cycle and can lead to anovulatory cycles (cycles without ovulation).
In general, it’s thought that marijuana can affect the production of luteinizing hormone in women. LH regulates testosterone production in men and stimulates female ovulation. When men smoke frequently, they tend to have lower levels of testosterone, and women who smoke frequently have less LH.
In addition to marijuana use, it’s important to examine other causes of late ovulation so you can put yourself in the best position for a successful pregnancy.
2. Lower sperm count
According to the Mayo Clinic, marijuana use can impair a man’s sperm count and ability to reproduce. Other research has suggested that marijuana is bad for men’s fertility.
However, a Harvard study surprisingly refutes those findings and states that there’s no evidence of harmful effects on fertility. In the study, researchers collected blood samples and semen from hundreds of volunteers at the Massachusetts General Hospital fertility clinic. In the study, which ran from 2000 to 2017, men were asked about their marijuana use. The results showed no correlation between marijuana use and male fertility.
Since there isn’t a conclusive determination on the subject, if you have a male partner who smokes, try to discourage him from doing so while you are trying to conceive — especially if his sperm count is low.
3. Deterioration of existing fertility problems
There’s no conclusive evidence that marijuana use causes infertility, but research has found that it can lower sperm count, increase anovulatory cycles, and disrupt the balance of hormones in the body that encourage pregnancy.
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