Research has not proven that cannabis causes miscarriage, but it has not cleared it either. Some studies report higher rates of pregnancy loss among people who use cannabis around conception or in early pregnancy, while others find no link once tobacco, alcohol, and other factors are accounted for. ACOG and the CDC both advise stopping cannabis before trying to conceive and during pregnancy because no safe amount has been established.
cannabis pregnancy doctor advice
Why isn't the evidence conclusive?
Most human data comes from self-reported use, and people often underreport cannabis, especially during pregnancy. Studies also struggle to separate cannabis from co-exposures like tobacco smoke, alcohol, and other substances that independently raise miscarriage risk. Small sample sizes and different definitions of use, from daily concentrates to occasional edibles, make results hard to compare.
marijuana and pregnancy research
What have studies on cannabis and miscarriage found?
Several cohort studies show an association between cannabis use and spontaneous miscarriage, particularly with frequent or heavy use near the time of conception. A smaller number of studies find the association weakens or disappears after adjusting for confounders such as smoking and socioeconomic factors. That pattern, an association without a confirmed mechanism, is why researchers describe the link as possible rather than established.
cannabis use while pregnant third trimester
How could cannabis affect early pregnancy?
THC crosses the placenta and reaches the developing embryo. The endocannabinoid system is involved in implantation and early placental development, so disrupting it is biologically plausible, though not proven in humans. Cannabis smoke also contains carbon monoxide and tar, which reduce oxygen delivery and add separate risk.
Cannabis Use While Pregnant: Third Trimester Risks and the Convenience Factor
Does the route of use matter?
No form of cannabis has been shown safe in pregnancy. Vaping and smoking deliver THC to the bloodstream quickly, while edibles produce a slower, longer-lasting exposure, but neither route changes the underlying concern about fetal exposure. Topical products are unlikely to produce meaningful blood levels, yet they are often not tested in pregnancy.
Is CBD or low-THC cannabis safer?
There is no evidence that CBD is safer than THC in pregnancy. The FDA advises against CBD use during pregnancy and breastfeeding, and CBD products are largely unregulated, so labels may not match contents. Low-THC flower still contains THC and other cannabinoids with unknown effects on a pregnancy.
What if I used cannabis before I knew I was pregnant?
Many people use cannabis in the first weeks before a positive test, and one exposure does not mean a pregnancy will fail. Stop use going forward and tell your clinician what you used, how often, and when, so they can factor it into your care. Being honest with your provider is more useful than trying to minimize the details.
When should you talk to a clinician?
- Before trying to conceive, if you use cannabis regularly or for nausea, sleep, or anxiety.
- If you have had a previous miscarriage and are unsure whether cannabis played a role.
- If you need help stopping, including withdrawal irritability or sleep disruption.
- If you are considering cannabis to treat pregnancy symptoms such as morning sickness.
The bottom line
Cannabis is not a confirmed cause of miscarriage, but it is not a confirmed safe exposure either. Given the uncertainty and the absence of any established safe threshold, the cautious path is to stop before conception and stay off it through pregnancy.