The Jury Is Still Out ln The Case Of Mary Jane vs Infertility
With marijuana legalization spreading quickly across the United States each successive November, the question of it’s impact on fertility has risen to the forefront of the reproductive community.
Limited studies over the course of the last 20 years have pointed to an association of marijuana and subfertiltiy. One 1990 study reported women smoking marijuana within a year of trying to conceive had a slightly elevated risk for infertility due to an ovulatory abnormality. A later 2007 study similarly found women who use marijuana had a slightly elevated rate of menstrual cycles that lacked ovulation.
More in depth studies on monkeys done in the 1980's looked at the biochemical effects of THC, the active ingredient in marijuana, on reproductive processes. They found that "acute Δ9-THC suppresses the release of gonadotropin-releasing hormone (GnRH) and thyrotropin-releasing hormone (TRH) from the hypothalamus, preventing these hormones from stimulating the release of prolactin and the gonadotropins, follicle stimulating hormone (FSH) and luteinizing hormone (LH), from the anterior pituitary."
Until recently, human studies, however, where limited to small sample sizes. A larger, more inclusive study recently published by the American Society for Reproductive Medicine in 2018, reviewed cross-sectional data from male and female respondents aged 15–44 years who participated in the 2002, 2006–2010, and 2011–2015 National Survey of Family Growth. Of 758 male and 1,076 female participants actively trying to conceive, 16.5% of men reported using any marijuana, versus 11.5% of women. Surprisingly, after analyzing the data, the time ratio to pregnancy for “never smokers” versus “daily users of marijuana” demonstrated no statistically significant impact of marijuana use on time to pregnancy.
You can interpret these studies in several ways but note that in human studies, control for the amount of marijuana used or other factors such as the use of alcohol or tobacco, was limited and could affect results. More studies are needed to rigorously examine the biochemical relationship of marijuana use and menstrual cycle irregularities in humans.
My personal recommendation to patients is to eliminate marijuana while trying to conceive. Both partners should abstain for six months. In men, marijuana was shown to have a negative impact on spermatogenesis and motility. Taking THC out of the picture will eliminate one more potential piece of the infertility puzzle.