Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

Approximately one in six couples “are unable to conceive after a year,” despite trying, “and are labeled infertile.” And in up to half the cases, it may be the man’s fault. There are “several lifestyle factors [that] have been associated with [diminished] sperm production,” such as smoking cigarettes. But what about smoking marijuana?

“Regular marijuana smoking more than once per week was associated with [about] a 28 percent …lower sperm concentration and…lower total sperm count,” based on a study of more than a thousand men. But “no adverse association was found for irregular use,” meaning less than once a week.

Now, this wasn’t a randomized study. And so, there may have been other factors that go along with regular marijuana use that could have really been to blame. But, they took into account cigarettes and alcohol and other drugs and STDs and things like that. But, there’s always a possibility there was something else for which they didn’t control.

Findings were similar for women. Hundreds of infertile couples were studied in California, and just like men had about a quarter fewer sperm, a quarter fewer eggs were retrieved from women using cannabis more than 90 times in their lifetime, or using the year before. Again, there could have been confounding factors, but until we know more, couples that are trying to conceive may want to make the joint decision to turn over a new leaf.

What about during pregnancy? Medical authorities recommend that women even “contemplating pregnancy should be encouraged to discontinue marijuana use,” and not use during pregnancy or lactation, though the Academy of Breastfeeding Medicine suggests the known benefits of breastmilk currently outweigh any potential harms for women who continue to smoke it. Despite these warnings from authorities, marijuana use has increased among pregnant women in recent years, up 60 percent. But that’s only from about 2.5 percent up to less than 4 percent, less than half the frequency of non-pregnant women.

Why are OB/GYNs so down on getting high? You’ll see scary articles in the American Journal of Obstetrics and Gynecology, making claims like this: a large study supposedly documenting a significantly increased risk for a serious birth defect. But, if you don’t just take their word for it, and pull up the actual study, you’ll see that the association wasn’t statistically significant after all. “Objective education [about marijuana and pregnancy] is good, but biased education is not.”

There have been some risks identified: infants may be “more likely to be [born] anemic, [or] have a lower birth weight, [or] require…intensive care,” compared to infants of mothers who do not use marijuana. But it’s “difficult to determine the direct effects of maternal cannabis use on the developing fetus because of” a variety of confounding factors, for which studies may not be able to completely control.

“Studies have also shown links between prenatal marijuana exposure and” learning problems later in life, manifesting years later at school, and that’s really where the greater concern lies: the potential long-term effects on brain development. So, even after weeding out the myths, there is enough concern that “pregnant and breast feeding [women] should [indeed probably] “be advised to either decrease or where possible cease cannabis use entirely.”

Please consider volunteering to help out on the site.