Cannabis and Embryo Viability: What Couples Should Know Before Trying

Cannabis use can significantly impact fertility and embryo health for both men and women. Here's what you need to know:

• For Women: THC disrupts egg development, increases chromosomal errors, and lowers embryo quality. A 2025 study found THC exposure reduced embryo euploidy rates from 67% to 60%.
• For Men: Heavy cannabis use can lower sperm count, concentration, and quality. However, some studies suggest low-to-moderate use may not drastically affect motility.
• Pregnancy Risks: Women using cannabis during fertility treatments face double the risk of pregnancy loss (54% vs. 26% for non-users).

Both partners should stop cannabis use at least 60–90 days before trying to conceive to improve fertility and reduce risks. Open communication with healthcare providers is key to navigating these challenges and optimizing your chances of a healthy pregnancy.

How Cannabis Affects Female Fertility and Embryo Development

THC and Egg Maturation Problems

When THC enters ovarian follicles, it disrupts the delicate environment essential for proper egg development.

One major issue researchers have identified is "accelerated maturation." THC seems to speed up the visible signs of egg maturation, but this process skips over critical developmental steps. As a result, eggs may look mature on the outside but lack the internal components they need to function properly.

The effects don’t stop there. THC significantly disrupts the meiotic spindle, the structure responsible for correctly dividing chromosomes during egg maturation. In lab studies, exposure to high doses of THC caused 92% of eggs to develop spindle abnormalities, compared to only 42% in untreated eggs. These abnormalities include multipolar spindles, disorganized microtubules, and misaligned chromosomes. Such defects greatly increase the risk of chromosomal errors, like aneuploidy.

THC also interferes with hormonal signaling. It suppresses the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus, which is essential for triggering the luteinizing hormone (LH) surge needed for ovulation. Without this surge, ovulation may not occur, leading to cycles where a woman has a period but does not release an egg.

Research Findings from Human and Animal Studies

The cellular disruptions caused by THC are mirrored in data from both human and animal studies.

For instance, women who used cannabis within a year before undergoing IVF treatment had 25% fewer eggs retrieved and 28% fewer eggs fertilized compared to those who didn’t use cannabis. The effects on embryo quality are even more concerning.

A study published in Nature Communications in September 2025 revealed that patients testing positive for THC had a 53% lower chance of achieving an embryo euploidy rate above 60% (odds ratio: 0.47). THC positivity also reduced the likelihood of reaching a 50% or higher blastulation rate by 55%.

The pregnancy loss data is perhaps the most unsettling. A 2019 prospective study found that women using cannabis during fertility treatments had double the adjusted probability of pregnancy loss - 54%, compared to 26% in non-users.

Animal studies shed light on these findings. For example, peripubertal mice exposed to THC experienced a 50% reduction in their ovarian follicle reserve and showed evidence of DNA damage in the remaining eggs. THC exposure also altered gene expression, affecting processes like chromosome segregation, extracellular matrix remodeling, and inflammation - all of which are vital for healthy embryo development.

Cannabis Use in Men and Reproductive Effects

Mixed Research Results on Sperm Quality

The relationship between cannabis use and male fertility is far from straightforward. A Danish study involving 1,215 young men revealed that using marijuana more than once a week was linked to a 28% drop in sperm concentration and a 29% decrease in total sperm count. Additionally, men who used cannabis had over twice the likelihood of having abnormal sperm morphology and were 2.76 times more likely to have semen volume below the World Health Organization (WHO) reference values.

Interestingly, another study reported contrasting results. It found that men who never used marijuana were more likely to have sperm motility below WHO standards (38.3%) compared to current users (21.1%). This has led to speculation that while heavy cannabis use is clearly harmful, low-to-moderate use might have a temporary "pro-spermatogenic" effect.

Dr. Omer A. Raheem, an Assistant Professor of Urology, weighed in on the matter:

"Marijuana use is common among men presenting for fertility evaluation, and may have a detrimental effect on semen quality, particularly morphology and volume, but may be protective against abnormal sperm motility."

For men already dealing with teratozoospermia (a condition involving abnormal sperm shape), quitting cannabis is strongly advised when trying to conceive. Cannabis use doubles the likelihood of abnormal sperm morphology, making it a significant risk factor. These conflicting findings highlight the need for more research to fully understand how cannabis use impacts male fertility and conception outcomes.

Effects on Conception and Pregnancy Success

When it comes to conception and pregnancy, the effects of cannabis use are just as complex. A 2021 study involving 722 IVF patients found that implantation rates were nearly identical between cannabis users (40.74%) and non-users (41.13%). Interestingly, the ongoing pregnancy rate was slightly higher among cannabis users (35.2% compared to 29.1%), though the difference wasn't statistically significant.

On the flip side, some studies suggest that male cannabis use could lower IVF fertilization rates. Given the high financial and emotional stakes of IVF, experts recommend that men abstain from cannabis for at least three months before trying to conceive. This allows for a full sperm production cycle, roughly 74 days, to occur without exposure to THC.

These findings, combined with earlier discussions on embryo development, emphasize the importance of taking a holistic approach to preconception health. While cannabis use might alter certain sperm parameters, these changes don't consistently lead to lower short-term pregnancy success. However, the potential for long-term effects, such as epigenetic changes in sperm DNA that could impact the health of future generations, remains an important area for further research.

Steps to Take When Planning Conception

When to Stop Using Cannabis Before Conception

Both partners should stop using cannabis at least 60 to 90 days before trying to conceive. This three-month period is crucial for a full biological reset. For men, it allows for a complete cycle of sperm production - about 74 days - ensuring new sperm develop without THC exposure. For women, this timeline supports hormonal normalization and improves egg quality, as eggs begin developing months before ovulation.

Since THC is stored in fat and can remain in the body for up to 30 days, this window ensures that metabolites are cleared, improving reproductive health. Open communication with your healthcare provider about your cannabis history is also important. This transparency helps them offer accurate fertility advice and tailor treatments, particularly if assisted reproductive technologies like IVF are being considered.

Once cannabis is out of the picture, the focus shifts to preparing your body for conception by optimizing overall health.

Lifestyle Changes to Improve Fertility

The 90-day preconception period is not just about eliminating cannabis - it’s also a chance to enhance your reproductive health. Focus on better nutrition, quality sleep, and effective stress management to naturally improve fertility. Women should track their menstrual cycles using tools like basal body temperature or ovulation strips, as it may take time for cycles to regulate after stopping cannabis.

Both partners should also address any substance use issues. If cannabis is being used for medical reasons such as anxiety or pain, consult a doctor for pregnancy-safe alternatives. Leading health organizations, including the American College of Obstetricians and Gynecologists (ACOG) and the U.S. Surgeon General, advise against cannabis use when trying to conceive due to its potential impact on fetal neurodevelopment.

Stem Cell Banking for Your Baby's Future Health

As you prepare for conception, consider long-term steps to protect your baby’s health beyond birth. One such option is stem cell banking, which provides valuable biological resources that could be used in future medical treatments.

Americord Registry offers a range of newborn stem cell banking services, including cord blood banking, cord tissue banking, placental tissue banking, and exosome preservation. These materials, collected at birth, are stored for decades and hold the potential to treat over 80 diseases, including certain cancers, blood disorders, and immune deficiencies. Cord tissue and placental tissue also house mesenchymal stem cells, which are being studied for their applications in regenerative medicine.

By opting for Americord’s CryoMaxx™ Processing technology and advanced 5-compartment storage vials, families can maximize cell recovery and maintain flexibility for future use. Americord provides various plans, from the Essential Family Plan (cord blood only) to the Maximum Family Plan, which includes both newborn and maternal exosome banking. This allows families to choose the level of protection that best suits their needs.

Starting with a healthy pregnancy free from cannabis exposure lays a strong foundation for your baby. Pairing that with stem cell banking creates a proactive approach to safeguarding their long-term health.

Conclusion: What Couples Need to Know About Cannabis and Conception

Understanding how cannabis affects embryo viability is essential for making informed decisions about reproductive health. Research shows that cannabis use can impact both partners' ability to conceive and maintain a healthy pregnancy. For instance, THC exposure has been linked to lower embryo euploidy rates (60% compared to 67%) and a doubled risk of pregnancy loss (54% vs. 26%). These findings highlight the challenges cannabis use can pose during conception.

"There is now sufficient evidence of harm to warrant avoiding use when attempting to conceive or when pregnant or lactating." - Jamie O. Lo, MD, Contemporary OB/GYN

The good news? Many of these effects are temporary. Sperm quality can improve within 74 days of stopping cannabis use, and female hormonal cycles typically stabilize within two to four months. A three-month break before trying to conceive is a practical step for couples aiming to optimize their fertility.

Honest communication with healthcare providers is also critical. One study revealed that 73% of THC-positive patients did not disclose their cannabis use on medical intake forms. This lack of transparency can prevent doctors from offering the best fertility advice, particularly for couples pursuing IVF. By sharing this information and planning ahead, couples can take meaningful steps toward improving their chances of a successful pregnancy.

FAQs

Does CBD (without THC) affect fertility or embryos?

Current research points to the possibility that CBD, even in the absence of THC, could affect fertility. Early studies on animals suggest that it may disrupt ovarian function, interfere with the ovarian cycle, and hinder follicular development and hormone production. For couples attempting to conceive, it’s important to weigh these potential effects when deciding whether to use CBD.

How can we tell if cannabis is impacting our fertility?

Cannabis use has been linked to potential effects on fertility. For men, it can lower sperm concentration, reduce motility (how well sperm swim), and even lead to abnormal sperm shape. In women, THC - the active compound in cannabis - might interfere with ovulation and make embryo implantation more challenging.

If you're concerned about how cannabis might be affecting your fertility, consider tracking changes in sperm quality or menstrual regularity after stopping for about 74 days (the typical cycle for sperm regeneration). Additionally, consulting a healthcare provider for fertility testing can offer more clarity. Taking a break from cannabis use could potentially support better reproductive health.

If we used cannabis recently, should we delay IVF or IUI?

Current studies indicate it might be wise to postpone IVF or IUI if there’s been recent cannabis use. Evidence points to cannabis potentially harming fertility and reducing embryo viability, which could affect the success of these treatments. To improve the chances of success, it’s worth waiting until the effects of cannabis have worn off before moving forward.