"Human eggs (oocytes) have receptors for cannabinoids made by our body, these receptors can also be activated by THC, the main psychoactive ingredient of Cannabis. This study used realistic concentrations of THC and its breakdown products to explore human oocyte physiology and also examined the outcomes of in vitro fertilization of eggs from people with Cannabis products in their system at the time their eggs were collected. Culturing immature eggs in THC changed the expression levels of some genes in the eggs and THC also affected the number of eggs with normal chromosome numbers at maturation. In the comparison study, patients who had consumed Cannabis around the time of egg collection had about 10% fewer fertilized eggs with a normal chromosome number compared to people who had not consumed Cannabis.

The study suggests that consumption of Cannabis might affect the outcome of IVF. The work did not address the potential effects of Cannabis consumption on natural conception. THC having effects on oocyte physiology is consistent with the presence of receptors for our body’s cannabinoids in the human reproductive system, and we are only beginning to understand the effects of real world Cannabis consumption on human reproduction. This work is an interesting step forward."

"This study investigated how cannabis, specifically tetrahydrocannabinol (THC), affects female fertility by combining laboratory experiments with a clinical case–control analysis. Researchers measured THC and its metabolites in the follicular fluid of women undergoing IVF. About 6% of samples tested positive, and most of those patients had not disclosed cannabis use. THC exposure was linked to higher oocyte maturation rates but significantly lower embryo euploidy rates (fewer genetically normal embryos).

In laboratory experiments, immature human oocytes exposed to physiologically relevant THC concentrations showed altered gene expression, disruption of the cytoskeleton, abnormal spindle formation, and increased chromosome segregation errors. These biological changes are consistent with a higher risk of producing abnormal embryos. The study therefore provides the first direct evidence that THC can impair egg quality and subsequent embryo development. A key strength of this research is that it not only demonstrates the negative impact of cannabis use on embryo quality but also provides a physiological explanation for this outcome."

Implications for Fertility Patients

"For women considering or undergoing fertility treatment, this research suggests that cannabis use may compromise reproductive outcomes—not by preventing fertilisation, but by reducing the likelihood of producing chromosomally normal embryos. Since embryo euploidy is closely linked to successful implantation and healthy pregnancy, cannabis exposure could prolong the time to conception and increase the risk of IVF failure and miscarriage."

Recommendations

"Based on these findings, fertility specialists should routinely ask about cannabis use, bearing in mind that patients often under-report. Clear, non-judgmental counselling should highlight the potential impact on embryo quality, the increased risk of failure to conceive, and the risk of miscarriage. Patients should be advised to avoid cannabis use while attempting conception or undergoing IVF, as even occasional use may expose oocytes to THC. Educational materials on reproductive health should include cannabis alongside other lifestyle factors such as alcohol, tobacco, and BMI. Larger prospective studies are needed to clarify dose–response effects, the impact of different cannabis preparations, and whether risks extend beyond IVF patients to natural conception."