Recent research indicates that marijuana may potentially harm oocytes (unfertilised eggs) in women, raising concerns about infertility, miscarriage, and genetic defects in newborns. The study published in Nature Communications highlights that elevated levels of tetrahydrocannabinol (THC)—the active compound in cannabis—are associated with changes in oocyte maturation and an increased risk of chromosomal abnormalities.
Dr Jamie Lo, an obstetrician and expert in obstetrics, gynaecology, and urology, stressed that these findings underscore the necessity for caution regarding cannabis use when planning for conception. The use of marijuana among pregnant women has been on the rise, with recent studies showing that its self-reported use has tripled in the U.S. from 2002 to 2020. This trend is concerning as various studies have linked cannabis consumption during pregnancy to increased risks of autism, low birth weight, premature births, and even infant mortality.
The current study fills a significant knowledge gap, focusing on the impact of cannabis on human oocytes and ovarian follicles—a previously unexplored area, as earlier research had primarily concentrated on its effects on sperm. The study found that higher THC concentrations affected the timing of oocyte maturation, influencing how chromosomes segregate and prepare for fertilisation.
While lead researcher Cyntia Duval noted that the study indicates a correlation rather than a direct cause-and-effect relationship, she emphasised the need for further research to confirm these findings and ascertain their implications for reproductive health. The investigation included over 1,000 ovarian fluid samples, comparing those from women who tested positive for THC with a control group. The results showed that THC-positive patients had a higher oocyte maturation rate but also exhibited a lower proportion of embryos with the correct number of chromosomes.
Moreover, THC exposure in immature oocytes resulted in structural changes that could hinder proper chromosomal separation—critical for healthy embryo development. These outcomes highlight the potential risks of cannabis use, particularly for individuals who might not be able to abstain and may benefit from harm-reduction strategies.
The potency of THC has increased significantly over the past few decades, with concentrations in legally sold cannabis now exceeding 40%. This heightened potency can complicate consumers’ understanding of their cannabis use. Women may inadvertently ingest higher THC levels than intended, which could negatively impact their reproductive health.
Experts recommend that individuals seeking to manage symptoms with cannabis consider safer alternatives or reduce their consumption frequency, given the uncertainty surrounding THC levels in cannabis products.