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Does THC Affect Fertility?

With the growing use of cannabis for both recreational and medical purposes, many people are beginning to question how it might affect their overall health, including their ability to conceive. One of the most frequently asked questions is whether THC, the psychoactive component of cannabis, can affect fertility in men or women.

This article is for couples trying to conceive, health-conscious individuals who use cannabis, and anyone curious about the possible effects of THC on reproductive health. We explore what the current science says, how THC may influence hormone levels and reproductive functions, and what steps users might consider if they are planning a pregnancy.

What Is THC and How Does It Work?

THC, or tetrahydrocannabinol, is the chemical responsible for most of cannabis’s psychoactive effects. It interacts with the body’s endocannabinoid system, which plays a role not only in mood, appetite and sleep, but also in hormonal regulation, sperm production, ovulation and implantation.

This system includes CB1 and CB2 receptors, which are found throughout the brain, reproductive organs and immune system. Because THC binds to these receptors, it has the potential to interfere with some of the processes required for natural conception.

How THC May Affect Male Fertility

Several studies have looked into how THC may impact sperm quality, hormone levels and overall fertility in men. The findings suggest that THC could negatively affect sperm in the following ways:

Reduced sperm count: Research indicates that regular cannabis use may lead to a lower sperm concentration
Decreased sperm motility: THC may reduce the ability of sperm to swim effectively
Abnormal sperm morphology: Cannabis use has been linked to a higher proportion of sperm with irregular shapes
Hormonal changes: THC may reduce levels of testosterone and disrupt the hormonal signals that regulate sperm production

These effects appear to be more pronounced with frequent or heavy use. Occasional or low-level cannabis use may carry less risk, but more research is needed to establish a safe threshold. A 2019 study published by researchers at Harvard found that men who had used cannabis in the past had slightly higher sperm counts than non-users, suggesting that the relationship between THC and fertility is complex and may be influenced by dose and frequency.

Does THC Affect Female Fertility?

THC may also influence female reproductive health. The endocannabinoid system is involved in regulating the menstrual cycle, egg maturation and embryo implantation. Disruption of this system through regular THC use could potentially lead to:

Irregular menstrual cycles
Delayed ovulation
Reduced chance of embryo implantation
Disrupted hormonal balance

Animal studies have shown that THC can affect levels of luteinising hormone (LH) and follicle-stimulating hormone (FSH), which are vital for ovulation. While human research is more limited, early findings suggest that cannabis may reduce the chances of becoming pregnant, particularly when used around the time of ovulation.

Effects on Pregnancy and Embryo Development

Even if conception occurs, continued cannabis use during early pregnancy may carry risks. THC crosses the placenta and can reach the developing embryo or foetus. Some studies have linked cannabis use in pregnancy with lower birth weight, developmental delays and a higher risk of miscarriage, though findings are not entirely consistent.

Because of this, the NHS advises pregnant women to avoid cannabis completely, including products that contain THC in any form. This recommendation also applies to those who suspect they may be pregnant or are actively trying to conceive.

Reversibility and Recovery

One important question for users is whether the potential effects of THC on fertility are permanent. In most cases, the answer is no. Many of the negative impacts observed on sperm health and hormone levels appear to be reversible after cannabis use is stopped. It may take a few months for sperm quality to return to normal, since sperm are produced in cycles lasting around 74 days.

For women, regular ovulation and hormonal balance often resume after stopping cannabis use, although this can vary depending on age, body weight and overall health.

What About CBD?

CBD, or cannabidiol, is a non-intoxicating compound also found in cannabis. It does not bind to cannabinoid receptors in the same way as THC and is not believed to impair fertility in the same way. However, many CBD products may contain trace amounts of THC, especially in unregulated or imported goods. It is important to choose products that meet UK safety standards if you are avoiding THC for fertility reasons.

Current Guidance and Recommendations in the UK

In the UK, medical cannabis is only available on prescription for specific conditions. Over-the-counter CBD products must contain less than 1mg of THC per container to comply with the law.

While there is no official fertility-specific advice regarding cannabis in UK legislation, both the NHS and British Fertility Society recommend avoiding cannabis use when trying to conceive. This advice applies to both partners, since fertility is a shared factor in most couples.

Should You Stop Using THC to Improve Fertility?

If you are actively trying for a baby, it is advisable to stop using THC-containing products. Reducing or eliminating cannabis use can help restore hormone levels, improve sperm health and increase the chances of a successful pregnancy. Even occasional use may affect sensitive stages of conception and early pregnancy.

Speak to your GP or a fertility specialist if you have concerns about reproductive health or if conception is taking longer than expected. They can advise on lifestyle factors and conduct fertility testing if necessary.

Conclusion

THC can affect fertility in both men and women, primarily by interfering with hormone levels, sperm function and the ovulation process. While these effects are often temporary and reversible, regular or heavy use of THC-containing products may lower the chances of conception and carry risks during pregnancy. If you are planning to conceive, it is wise to avoid THC entirely and speak to a medical professional for tailored advice.