Cannabis and fertility: what you need to know before trying to conceive

Cannabis and fertility: what you need to know before trying to conceive

Key takeaways

• New research suggests THC, the active compound in cannabis, may damage eggs and increase the risk of chromosomal abnormalities, miscarriage and failed fertilisation
• This applies to all cannabis products – oils, edibles, medicinal and recreational forms – not just smoking
• THC levels in the blood mirror those in follicular fluid, meaning all eggs are directly exposed to the same concentration
• If you are trying to conceive naturally or through IVF, my advice is clear: avoid cannabis in all forms
• Women using cannabis for endometriosis pain or anxiety should speak with their doctor about safer alternatives before trying to conceive

Cannabis use is becoming increasingly common in Australia – for anxiety, for pain management, and particularly among women managing endometriosis symptoms. At the same time, I am seeing more patients who are either unaware of the potential impact on their fertility, or unsure whether the products they are using are a concern.

New research has given us the clearest picture yet of what THC – the active compound in cannabis – may be doing to female fertility. And based on what the evidence shows, my advice is straightforward: if you are trying to conceive, or planning to, cannabis products should be off the table entirely.

What the research found

This study, led by researchers at the University of Toronto, is the first of its kind to examine THC’s effect on the human egg and ovarian follicle directly. Previous research had focused on THC’s impact on sperm – where it has been shown to reduce count, motility and structure – but the female side of the equation had not been studied in this way before.

The researchers analysed follicular fluid samples from more than 1,059 IVF patients. Of these, 62 tested positive for THC metabolites. What they found was that higher levels of THC in the follicular fluid were associated with eggs maturing more quickly but with fewer being chromosomally normal. This means those eggs were less likely to fertilise successfully, and more likely to produce embryos with chromosomal defects.

The study concluded there was compelling evidence that cannabis consumption may negatively impact female fertility. Independent lab experiments, in which immature donor eggs were directly exposed to THC, produced similar abnormalities – lending further weight to the findings.

The lead researcher was careful to note that the study shows an association rather than direct cause and effect, and that more research is needed. That is a fair scientific qualification. But the direction of the evidence is clear enough that I do not think patients should wait for a definitive answer before acting on it.

Why this matters specifically for IVF patients

One of the most important findings for anyone going through IVF is this: THC levels in the blood are mirrored in the follicular fluid. This means that if you are using cannabis products, all of your eggs are being exposed to the same concentration of THC – not just some of them.

For women undergoing IVF, where the goal is to retrieve and fertilise as many viable eggs as possible, anything that increases the rate of chromosomal abnormality is directly working against your chances of success. Chromosomal abnormalities in embryos are also a leading cause of miscarriage and failed implantation.

The research also raises a concerning possibility: that higher THC exposure could elevate miscarriage risk in younger women to levels more typically associated with older patients. Age-related chromosomal disruption is one of the main reasons fertility declines with age – if THC is causing similar disruption, the implications for younger women using cannabis are significant.

What counts as a cannabis product?

This is a question I get asked regularly, and it is worth being specific. The concern is not limited to smoking cannabis. THC is present across a wide range of products, including:

• Cannabis oils and tinctures
• Edibles such as capsules, gummies and baked goods
• Medicinal cannabis prescribed for anxiety, pain or sleep
• Products used for endometriosis symptom management

If a product contains THC, it carries the same potential risk. The route of administration does not change the underlying exposure.

It is also worth noting that THC metabolises into various other compounds in the body, some of which may also be harmful – so the risk is not limited to THC alone.

A note on cannabis for endometriosis and anxiety

I understand that many women who are using cannabis products are doing so because they are managing real, difficult symptoms – endometriosis pain, anxiety, sleep difficulties. These are not trivial concerns, and I am not dismissing them.

But if you are also trying to conceive, it is important to weigh that use carefully against what the evidence now suggests about fertility risk. There are other management options for both endometriosis and anxiety that do not carry these concerns, and I would encourage you to have that conversation with your specialist before trying to conceive.

If you have endometriosis and are planning a pregnancy, this is exactly the kind of conversation we should be having together – because endometriosis itself can affect fertility, and managing it well before and during conception attempts matters enormously.

My advice

Based on the findings, my advice is clear. If you are trying to conceive naturally or through IVF, you should not be using cannabis products in any form. This includes medicinal cannabis prescribed by a doctor.

If you are currently using cannabis and are planning to conceive, speak with your specialist about how to safely transition away from it, and what alternatives might be appropriate for the symptoms you are managing.

If you have questions about how to optimise your fertility before trying to conceive, or want to understand how factors like cannabis use might be affecting your chances, get in touch to book a consultation.

References

Duval C et al. University of Toronto. Study on THC and female fertility, as reported in The Age, September 2025. Read the full article here