Marijuana exposure may damage female eggs in ways that could increase the risk of infertility, miscarriage and genetic defects in babies, new research has found.
The study, published in Nature Communications, analysed more than 1,000 ovarian fluid samples from patients undergoing fertility treatment. Researchers compared oocytes from 62 women who tested positive for THC, the main psychoactive compound in cannabis, with those from women who did not use the drug.
They found that eggs exposed to THC matured more quickly but were more likely to have chromosomal abnormalities, raising the risk of developmental problems if fertilised. In laboratory experiments, immature oocytes exposed to THC also showed abnormalities in spindles, the structures that ensure chromosomes divide properly.
“Chromosomes need time to align perfectly to create healthy embryos,” said study author Cyntia Duval, who conducted the research at the University of Toronto. “We saw more mature eggs, but at what price if they don’t have the right number of chromosomes?”
Dr Jamie Lo, an obstetrician at Oregon Health & Science University who was not involved in the study, called the findings “concerning” and said they underscored the need for caution among women planning to conceive.
Cannabis use during pregnancy has been linked in previous studies to autism, low birth weight, preterm delivery and even infant death. Use among pregnant women in the United States has tripled between 2002 and 2020, according to government surveys.
Duval stressed that the findings show only an association rather than causation, and called for more research. Still, experts said the results could support harm-reduction strategies, encouraging women who cannot abstain to reduce cannabis use to protect fertility and improve pregnancy outcomes.
