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How Marijuana Can Affect Fertility

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.

Female Fertility

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.

Male Fertility

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.

Learn about whether marijuana can cause infertility, including a review of research on marijuana's effects on women and men.

Marijuana may impair female fertility

Female eggs exposed to THC, the psychoactive ingredient in marijuana, have an impaired ability to produce viable embryos, and are significantly less likely to result in a viable pregnancy, according to an animal study accepted for presentation at ENDO 2020, the Endocrine Society’s annual meeting.

Marijuana, or cannabis, is the most commonly used recreational drug by people of reproductive age. The rise in marijuana use has occurred at the same time that THC percentages in the drug have increased. “Currently, patients seeking infertility treatments are advised against cannabis use, but the scientific evidence backing this statement is weak,” said Master student Megan Misner, part of the research laboratory led by Laura Favetta, Ph.D., in the Department of Biomedical Sciences at the University of Guelph in Canada. “This makes it difficult for physicians to properly advise patients undergoing in vitro fertilization.”

In the new study, researchers treated cow oocytes, or female eggs, with concentrations of THC equivalent to therapeutic and recreational doses. The oocytes were collected and matured into five groups: untreated, control, low THC, mid THC and high THC.

The eggs’ developmental rates and gene expression were measured. The researchers evaluated the ability of embryos to reach critical stages of development at specific time points. With higher concentrations of THC, they found a significant decrease and delay in the ability of the treated oocytes to reach these checkpoints. “This is a key indicator in determining the quality and developmental potential of the egg,” Misner said.

THC exposure led to a significant decrease in the expression of genes called connexins, which are present at increased levels in higher quality oocytes. Poorer quality oocytes, with lower connexin expression levels, have been shown to lead to a poorer embryo development. “This embryo would be less likely to proceed past the first week of development, and thus lead to infertility,” Misner said.

Preliminary data also showed THC affected the activity of a total of 62 genes in the treatment groups compared with the non-treated groups. “This implies lower quality and lower fertilization capability, therefore lower fertility in the end,” she said.

Female eggs exposed to THC, the psychoactive ingredient in marijuana, have an impaired ability to produce viable embryos, and are significantly less likely to result in a viable pregnancy, according to an animal study.