Cannabis and Fertility

Cannabis use appears to negatively impact both male and female fertility, though the evidence is stronger for effects on sperm parameters than for female fecundability.

Background

In 1996, California marked a turning point in U.S. drug policy by becoming the first state to legalize medical cannabis through the passage of Proposition 215. In the decades that followed, cannabis laws expanded and shifted nationwide, leading to a steady rise in cannabis use for both medical and nonmedical purposes. Over the same period, fertility rates have declined markedly in the United States and across the globe, raising questions about how these concurrent trends may be connected.

Introduction

According to the CDC, as of February 2024, 47 states, the District of Columbia, and three U.S. territories (Guam, Puerto Rico, and the U.S. Virgin Islands) allow the use of cannabis for medical purposes, while 24 states also permit nonmedical use. Prior to the release of these figures, a study from Carnegie Mellon University’s Heinz College found that between 2008 and 2022, cannabis use in the United States increased by 120%, with the number of days of use per person rising by 218%.

In April 2025, the CDC shared the U.S. Total Fertility Rate (TFR) for 2024. This number comes from almost all (99.92%) of the birth records collected and processed by the National Center for Health Statistics by February 4, 2025. The report shows that in 2024, the fertility rate in the U.S. fell to a record low of 1.599 births per woman. This continues a long-term downward trend and is well below the 2.1 births per woman needed to keep the population stable.

While the TFR number reflects a complex mix of factors—including intentional choices such as delaying or forgoing children, economic pressures like rising living and housing costs, and broader social shifts related to women’s education and careers—infertility also plays a role. Defined as the inability to become pregnant after one year of regular, unprotected sex, infertility has been on the rise for the last 20+ years. A 2022 report published in Fertility and Sterility estimated an infertility rate of 6.9% in 1995, rising to 8.1% in the 2017–2019 survey cycle. In May 2024, the CDC reported that 1 in 5 married women aged 15 to 49 with no prior births (19%) were unable to become pregnant after one year of trying. Additionally, about 1 in 4 women in this group (26%) experienced difficulty either becoming pregnant or carrying a pregnancy to term.

How Does Cannabis Affect the Body

The body has its own built-in system, called the endocannabinoid system (ECS), which uses natural, cannabis-like molecules to help maintain balance by regulating vital functions like mood, sleep, appetite, pain, memory, and immune response. This system uses two main receptors to carry out its work: CB1 and CB2. When cannabinoids from outside the body (exocannabinoid) are consumed, they can affect the endocannabinoid system by activating these receptors more strongly or for longer than the body’s own cannabinoids.

CB1 Receptors

The CB1 receptors, which are abundant in the brain, are involved mainly in memory & learning, decision-making & impulse control, reward & motivation, emotion & fear, and movement & coordination. When THC binds to CB1 receptors, it reduces the release of neurotransmitter - neurons fire less precisely and neural timing and coordination are altered. This leads to effects such as: euphoria or relaxation, altered perception of time, impaired short-term memory, reduced attention and reaction time, changes in anxiety (can reduce or increase it, depending on dose/context).

Sperm and THC

Just like the brain, sperm cells have CB1 receptors. These receptors help regulate sperm production, movement (motility), timing of sperm maturation, and the ability to fertilize an egg. When THC activates CB1 receptors more strongly and for longer than normal, these processes are disrupted.

Egg and THC

Again, just like the brain, egg cells (oocytes) and the surrounding ovarian tissue have CB1 receptors. These receptors help coordinate egg maturation, hormone signaling, the timing of ovulation, and early embryo development. When CB1 receptors are activated more strongly and for longer than the body’s own cannabinoids would normally allow, these finely timed processes can be disrupted. When THC overstimulates CB1 receptors, ovulation can be altered, and eggs may mature too slowly or incompletely, reducing their ability to be fertilized or develop normally afterward.

CB2 Receptors

CB2 receptors are found mainly in the immune system, but they are also present in reproductive tissues in both males and females. Their main job is to control inflammation and immune balance. Successful reproduction requires a very precise immune balance, where enough immune activity is required to protect tissue, but not so much that sperm, eggs, or embryos are treated as threats. CB2 receptors help keep this balance by reducing inflammation, and calming immune responses in reproductive tissues. This is especially important for sperm survival, egg quality and embryo implantation.

Cannabis and Male Fertility

Cannabis use has been associated with adverse effects on male reproductive health, including reduced sperm count and concentration, abnormal sperm morphology, decreased motility and viability, and impaired fertilizing capacity. A systematic review published in the Journal of Urology in 2020 examined the potential effects of cannabis on male fertility. After incubating sperm with THC at therapeutic and recreational concentrations for three hours, researchers measured sperm motility using computer-assisted semen analysis. They reported that:

“ The most extensive body of evidence for cannabis-related alterations to sperm is for sperm motility.”

The study further notes that “these various investigations suggest that, through the action of cannabis on the CB1 receptor, the mitochondrial activity of sperm is reduced, resulting in significantly impaired motility.”

The study concluded that:

“ Studies demonstrate reduced sperm count and concentration, morphological changes, reduced motility and viability, and decreased fertilizing capacity in animals and humans exposed to marijuana or cannabis derivatives

Cannabis and Female Fertility

Cannabis use appears to negatively affect female fertility, although findings across studies are mixed. The most consistent observation is reduced fecundability (the ability to conceive), particularly among women who use cannabis regularly.

A cross-sectional analysis of 3,167 women aged 20 to 49, conducted between 2013 and 2018, compared women who had never used cannabis with those who reported regular use. The researchers found that women with frequent cannabis use had 53% greater odds of infertility, concluding that:

“ Our results suggest a possible modest association between regular cannabis use and infertility, adding to a growing body of evidence which can inform professional society recommendations and patient counseling."

Cannabis use negatively affects oocyte quality and can disrupt ovulation. A study published in Nature Communications in 2025 examined follicular fluid and granulosa cells collected during egg retrieval from IVF patients who used cannabis and those who did not. The study found that THC concentration in follicular fluid was positively correlated with oocyte maturation, and that THC-positive patients had significantly lower embryo euploid rates compared with matched controls.

Conclusion

Despite the growing prevalence of cannabis use in the United States, research examining its effects on fertility remains limited and, in some areas, inconclusive. While findings across studies are mixed, emerging evidence suggests that regular cannabis use may negatively affect reproductive outcomes, including reduced fecundability and alterations in gamete quality. To date, most research has focused on male fertility, with comparatively fewer studies investigating the effects of cannabis use on female reproductive health.