With a federal rescheduling proposal on the way and many states decriminalizing possession or use, marijuana is more widely available than ever before. While state-approved growers can ensure the end result is more consistent and safer, there are still lots of questions about the long-term effects marijuana can have on our bodies.

First things first, a disclaimer

Published studies have limitations, and today’s strains typically have higher levels of THC than past strains. Some animal testing measured the results of intravenous marijuana exposure rather than through smoke or edibles. Other older studies considered “heavy use” to be anything more than 3 times a month. Some studies noted that the participants smoked both tobacco and marijuana, so it was hard to distinguish which substance was impacting fertility more. Read more about past studies.

The biggest thing to keep in mind: results aren’t perfect, and we still have a lot to learn about the impact of marijuana.

Here’s what we do know:

Marijuana impacts male fertility

Several studies show that chronic (think daily) use of marijuana can cause lower sperm count, which can limit the number of good quality sperm that can reach an egg. Other studies showed that marijuana can impact sperm morphology (shape) or motility (ability to swim toward an egg), but a lower sperm count is the most consistent symptom for regular users. 

Marijuana also impacts female fertility

It doesn’t seem to impact the amount of time it takes a woman to get pregnant, but a study from 1990 shows that women who had smoked in the past year were twice as likely to have trouble conceiving because of ovulatory dysfunction than non-users. 

Marijuana impacts the outcomes of assisted reproductive technology like IVF

A study of 221 patients followed women who had smoked in the year leading up to IVF. Those women retrieved 25% fewer eggs, and 28% fewer of their eggs fertilized into embryos. These women were also more likely to experience pregnancy loss. 

There isn’t evidence that marijuana use causes stillbirth or miscarriage. 

Marijuana impacts pregnancy and fetal development 

Marijuana use during pregnancy is associated with lower birth weights, pre-term deliveries, and NICU admissions, but that’s coming from inconsistent results from past studies. Some reports show that prenatal marijuana use impacts neurological development in babies and school-aged children, including a lower attention span, anxiety and depression symptoms, and difficulty problem solving.

Wrapping up

Overall, results seem to indicate that marijuana can lead to negative outcomes in people who have existing fertility concerns. If you (and your partner, if you have one) use marijuana and are trying to conceive or planning to start treatment, talk to your doctor about their recommendations. To give you the best chance at a healthy pregnancy, they may suggest cutting back or stopping altogether.

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