A recent study has raised concerns that cannabis use could reduce the chances of a successful pregnancy through in vitro fertilisation (IVF). Researchers in Canada examined over 1,000 samples of fluid taken from around developing eggs during IVF treatment. In a small proportion of these samples, they detected traces of tetrahydrocannabinol (THC), the main psychoactive compound in cannabis.Read More
When eggs developed in fluid containing THC, they were more likely to show chromosomal abnormalities. Chromosomes carry the genetic material necessary for healthy embryo development, so errors at this stage can lead to failed fertilisation, miscarriage, or longer times to achieve pregnancy. The eggs exposed to THC also matured at faster rates than those from patients with no signs of cannabis in their samples, which may be another sign of disrupted development.
What the Study Found
In the first part of the research, 1,059 fluid samples from IVF patients were analysed. Out of these, 62 contained detectable levels of THC. Eggs linked with these samples were more likely to show signs of genetic errors compared with those where no cannabis traces were present.
The researchers went further, conducting controlled experiments with unfertilised eggs from 24 consenting patients. They again found that when THC levels were higher, the number of chromosomal errors in the eggs increased. The eggs exposed to cannabis also tended to mature earlier than expected, which could affect the timing of fertilisation and embryo development.
While the results were clear, the researchers stressed that the sample size was small. This means factors like the age of the women, which is already the single biggest risk factor for declining egg quality, could not be fully accounted for. Still, the findings add to growing evidence that cannabis use may not be safe for people trying to conceive.
Why This Matters for IVF Patients
Chromosomal health is central to the success of IVF. An egg with the correct number of chromosomes is more likely to create a healthy embryo that can implant and grow into a pregnancy. Eggs with abnormalities are a major reason why IVF cycles fail or why miscarriages occur.
If cannabis use increases the number of chromosomal errors, it could make IVF less effective. Patients may need more treatment cycles to achieve a pregnancy, or they may face higher risks of failed implantation. For people already dealing with the stress and cost of fertility treatment, any factor that reduces egg quality is significant.
Broader Fertility Concerns
The new research adds to earlier findings from animal studies showing that THC can negatively affect embryo development. Human studies have also suggested that regular cannabis use may be linked to infertility in both men and women. Past research has connected cannabis with lower sperm quality as well, meaning it may affect fertility outcomes for both partners.
While cannabis has recognised medical uses, such as pain relief or easing anxiety, it is not recommended during pregnancy. Experts say it may also be wise to avoid cannabis when trying to conceive, particularly when undergoing fertility treatments such as IVF.
The Safest Approach for Conception
For couples hoping to have children, the safest option is to avoid cannabis in the months leading up to and during fertility treatment. This is especially important since even moderate use could interfere with the delicate processes of egg development, fertilisation, and early embryo growth.
Although more research is needed to confirm the full extent of the risks, the existing evidence suggests that cannabis use adds another potential obstacle for people trying to conceive. IVF is already a challenging and emotional journey for many families, and reducing preventable risks can only help improve outcomes.
Conclusion
The latest study highlights an emerging concern: cannabis use may harm egg quality and reduce the success of IVF by increasing chromosomal abnormalities. While the research is still limited, the potential impact on fertility is enough to warrant caution. Until larger studies provide more answers, avoiding cannabis before and during fertility treatment is the most responsible step for those hoping to start or grow their families.
Reference: https://www.nature.com/articles/s41467-025-63011-2