What you should know about marijuana and fertility

Trying to conceive? Fertility specialists at Western University say you should understand the facts about marijuana and its potential effect on sperm count and ovulation. In a practice article and podcast for CMAJ, Drs. Sara Ilnitsky and Stan Van Uum, take a look at the five things you should know about marijuana and fertility.

“When marijuana became legal for recreational use in October 2018, there was a lot of discussion in the fertility world about how it might affect patients with fertility concerns,” said Dr. Ilnitsky a clinical fellow in reproductive endocrinology and infertility at Western’s Schulich School of Medicine & Dentistry who practises at The Fertility Clinic at London Health Sciences Centre. “Legalization will likely increase marijuana use among reproductive-aged men and women, so we wanted to help inform health care providers of what we do and do not know about marijuana’s effect on fertility.”

The five points they highlight in the paper are:

1. The active ingredient in marijuana, tetrahydrocannabinol (THC), acts on receptors found in the hypothalamus, pituitary and internal reproductive organs in both males and females.
2. Marijuana use can decrease sperm count. Smoking marijuana more than once a week is associated with a 29 per cent reduction in sperm count.
3. Marijuana may delay or prevent ovulation.
4. Marijuana may affect the ability to conceive in couples with infertility but does not appear to affect couples without fertility issues.
5. More and better quality research is needed into the effects of marijuana on fertility.

“The general public’s knowledge about the effects of marijuana on fertility is limited. This is equally true of health care providers’ knowledge and relates to the lack of available evidence,” Dr. Ilnitsky said.

The authors hope this paper will provide an evidence-based source of information for marijuana users and health care providers, and say they hope it will also help prompt more rigorous scientific study in this area.

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The Schulich School of Medicine & Dentistry at Western University is one of Canada’s preeminent medical and dental schools. Established in 1881, it was one of the founding schools of Western University and is known for being the birthplace of family medicine in Canada. For more than 130 years, the School has demonstrated a commitment to academic excellence and a passion for scientific discovery.

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