Since it’s 4/20, the official day to celebrate all things cannabis, we’re nerding out by writing about the green stuff and fertility stuff. As you likely know, smoking cigarettes (AKA tobacco) during pregnancy is a big “no no.” This goes right along with the same set of pregnancy diet recommendations we often hear: no smoking, no drinking, no raw fish, take a prenatal vitamin, etc.
The American College of Gynecologists and Obstetricians (ACOG) advises that pregnant women avoid smoking marijuana, too. Dr. Dana Gossett, an OB-GYN, tells NPR that research shows smoking marijuana while pregnant increases the risk of stillbirth and can negatively impact a child’s visual-motor coordination. The psychoactive compounds in marijuana—known as THC—can be passed from the mother to the fetus via the placenta when you smoke marijuana or consume it orally (AKA edibles, like pot brownies).
But what if we’re not thinking about getting pregnant for a while? Could enjoying marijuana now negatively impact our ability to conceive later? I’ve personally used marijuana to manage menstrual cramps, for example. “Any person who is pregnant or contemplating pregnancy should be encouraged to discontinue their use of marijuana by their medical provider,” says Stefani Davis, a Women’s Health Nurse Practitioner (WHNP). “Counseling women on the potential effects of marijuana on their reproductive health is of utmost importance as they consider pregnancy, as early education could save them from stress and complications of infertility that could have been avoided without the use of marijuana.”
But Davis adds that many of the studies on marijuana and fertility have been performed on rats. As much as we love Pixar’s Ratatouille, this does not give us a complete understanding of the issue. Plus, her opinion may be up for debate. This 2018 study published in Fertility and Sterility found that marijuana use had no effect on time to pregnancy (TTP) based on a population of over 1,000 women and over 700 men actively trying to conceive.
Confusing right? It seems that right now, choosing not to smoke weed if pregnancy is a desired part of your future is more of a “better safe than sorry” approach than one that’s widely accepted by the medical community. Unfortunately, science doesn’t always have the conclusive answers we crave. To break down what science does know (and commemorate 4/20, of course) we looked into the research that’s out there to understand how marijuana is related to fertility.
How the heck can marijuana impact my vagina?
The same reason your mind may feel more calm or clear-headed after physically exercising. The body’s systems are interrelated and help each other out in many ways. The body’s Endocannabinoid System (ECS) is devoted to mediating the effects of marijuana when it enters the bloodstream after being smoked or taken orally. Though they may seem unrelated, the ECS is closely linked to the reproductive system and helps it properly function. As this comprehensive 2016 report on marijuana and fertility research explains, endocannabinoid receptors (which are part of the ECS) are “distributed extensively throughout the human body.” This includes the ovaries, fallopian tubes, and endometrium. For example, the report explains the ECS is active in the ovaries during folliculogenesis—the process that produces mature eggs from ovarian follicles. In both rat and human ovaries, endocannabinoid receptors were found in follicle cells in several stages of maturity.
When the ECS and its receptors are activated by cannabis in the bloodstream, reproductive function is therefore impacted. Essentially, marijuana causes the ECS to work differently in the body and neglect its everyday responsibilities. According to the study’s authors, “Altered ECS expression is associated with reduced fertility, ectopic pregnancy and spontaneous abortion.”
Don’t freak: Like we mentioned earlier, the authors agree there’s much more work to be done and a need for additional studies on humans—not our furry friends—to fully understand the issue. Let’s look into their conclusions further, specifically regarding fertility.
Marijuana and the menstrual cycle
The menstrual cycle has a lot do with fertility. In order to naturally conceive, the ovaries must release an egg—a process known as ovulation—for a sperm to fertilize it. According to the study mentioned above, there is an association between marijuana and menstrual cycle disruptions.
“Women who use marijuana have a slightly elevated rate of menstrual cycles that lack ovulation,” write the authors. “One study found an association between occasional marijuana use (self-reported 1 to 3 times in the three months preceding the study) and prolonged follicular phase (3.5 days), resulting in delayed ovulation.” The follicular phase of the menstrual cycle is when a few ovarian follicles—which house eggs—develop in preparation for ovulation. But only one of these follicles will release a fully matured egg. If the follicular phase is delayed, ovulation—which enables conception—is thus also delayed.
A separate study focused on moderate-to-heavy marijuana users (at least 3 times per week over the six months preceding the study), found that individuals were more likely to experience menstrual cycles that were anovulatory (a science-y word for a complete absence of ovulation). But, as the study points out, these experiments were performed on small sample sizes and did not take into account the exact dosage of marijuana or if other substances like alcohol or tobacco were used, which can also impact fertility. The authors write, “Therefore, the results of these studies should be interpreted with caution.”
Marijuana and fertility hormones
Let’s take things one step further: The menstrual cycle is regulated and fueled by hormones, like estrogen, progesterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH), to name a few. Modern Fertility tests for all of these with the exception of progesterone. If marijuana impacts the menstrual cycle, it probably influences these hormones, too. Here’s a recap of these hormones’ responsibilities in the phases of the menstrual cycle from UCSF Health:
Follicular Phase: LH and FSH stimulate the growth of several ovarian follicles—kicking things off. As the “dominant” follicle (the one that will release an egg) grows, estrogen rises to prep for ovulation and FSH levels begin to fall. This drop in FSH causes the other ovarian follicles (with the exception of the dominant one) to die off.
Ovulation: When estrogen levels peak, the body produces a surge of LH, which helps the egg reach final maturation and ultimately release from the follicle.
Luteal Phase: The increase in LH cues the body to produce progesterone, which helps the lining of the uterus thicken in anticipation of a fertilized egg making its home there (it’s like making a comfier bed for the baby). If a sperm fertilizes the egg and pregnancy occurs, progesterone levels continue to rise. If fertilization doesn’t occur, progesterone levels drop.
Menstrual Phase: This drop in progesterone causes the egg and the uterine “bed” to shed in the form of your period.
The point is: Reproductive and fertility hormones work together and often take their cues from each other to make all the magic happen.
Here’s one example from the report of how marijuana impacts these hormones: LH and FSH are types of “gonadotropins,” the categorical name for hormones released by the pituitary gland. The report says that THC can suppress the release of gonadotropins, including LH and FSH. This means the entire menstrual cycle can get thrown out of whack when marijuana enters the picture. “The gonadotropins maintain the menstrual cycle by promoting ovarian follicle maturation, stimulating production of the ovarian steroids estradiol and progesterone, and inducing ovulation, and alterations in circulating gonadotropin can disrupt these processes,” write the authors.
Studies included in the report show that inhaling 1 gram of marijuana is enough to suppress LH levels during the luteal, but not follicular, phase of the human menstrual cycle. As a reminder, the luteal phase refers to post-ovulation, when the body is prepping for either pregnancy or menstruation. But as noted above, a surge in LH is what cues the body to produce progesterone and create the uterine “bed” for the baby. The authors say, “Suppressing LH during the early luteal phase may terminate early pregnancies by reducing ovarian production of progesterone, a hormone that is necessary to maintain and support pregnancy.”
What this means for you
We, along with the medical community, can’t say it enough: There aren’t sufficient recent studies with large (human) sample sizes to conclusively know how marijuana impacts fertility, especially in the long-term. Does smoking or enjoying edibles affect us down the road? TBD. While some studies say it’s a non-issue, others suggest the exact opposite. In the meantime, we’ll be keeping our eyes peeled for committee opinions from governing organizations like ACOG that dictate practice guidelines in the field of women’s reproductive health.
To be honest, the medical community is not in a place to tell you whether you should light up in celebration of 4/20 without worrying about it. But they’re not going to tell you to hide your pot like you’re back in high school, either. (If you’re pregnant, however, definitely hide it—not using marijuana while pregnant is something the doctors currently agree on.) When in doubt, we always suggest reaching out to your provider or a fertility specialist. By putting your heads together, you can make an informed decision that combines a number of relevant variables like professional expertise, the available clinical research, your health goals, and your current needs and lifestyle.