A new study cautions high levels of cannabis use could harm chances of falling pregnant through in vitro fertilization (IVF).

Testing 1,059 samples of follicular fluid from around the developing eggs of patients undergoing IVF treatments, University of Toronto embryologist Cyntia Duval and colleagues found 62 that were positive for tetrahydrocannabinol (THC).

Immature egg cells (oocytes) from fluids with higher levels of THC were more like ly to have chromosomal abnormalities. These oocytes also tended to mature at faster rates than the matched controls that had no traces of THC in their surrounding follicular fluid.

"The study suggests that consumption of cannabis might affect the outcome of IVF," says pharmacologist Mark Connor from Macquarie University, who was not involved in

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