Is Cannabis Safe During Pregnancy?
How Advocacy Groups Twist the Research
By Avery Martz | Updated August 2026
The Short Answer
Many people have already noticed the problems with the cannabis advocacy playbook. Convince the public that smoking cannabis has legitimate medical uses, then convince them smoking cannabis is relatively harmless. Convince enough people of those two things, and cannabis will be legalized.
But those are two very different claims: evidence that cannabis can have legitimate medical uses is not evidence that smoking cannabis is harmless, particularly for vulnerable populations.
The most offensive example of this playbook in action is how advocacy groups approach the topic of cannabis and pregnancy. Pregnancy represents an extreme test of the harmlessness narrative. If cannabis can be presented as safe enough for pregnant women, concerns about ordinary recreational use become much easier to dismiss.
Instead of presenting evidence as it exists and encouraging extreme caution, these groups seem determined to push the evidence in a direction that supports their agenda.
Rather than claiming outright that cannabis is safe during pregnancy, a claim the evidence does not support, advocacy groups assemble collections of studies showing prenatal cannabis exposure may not be associated with certain adverse outcomes. Each narrow finding is presented individually, creating a broader narrative that none of the individual studies can support.
This is a form of idea laundering. Begin with an unpalatable conclusion and pass it through apparently legitimate intermediaries until it becomes acceptable to the intended audience. Find research that can be interpreted in your favor. Select the right quotations. Write the most favorable headline.
Never question results that align with your incentives. Never present results that don't. The studies can be real. The quotations can be accurate. The individual findings can be legitimate. But the narrative is still bullshit.
In my reading of the research, there is no good evidence establishing that cannabis use during pregnancy is safe. At Herbal Edge, we therefore defer to the precautionary principle: when serious harm is plausible and scientific certainty is lacking, caution and preventive action are appropriate.
A broader summary of the evidence surrounding cannabis and pregnancy can be found in The CBD Wiki →. Here, I want to do something else.
Let's look at some of the research that has been making headlines recently and follow what happens between what a study actually found and what advocates want you to believe it means.
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Never Question Useful Results
The first rule of cannabis advocacy is never to question results that support the narrative.
In this example a study looked at a large population of high-risk children and divided them into groups based on prenatal exposure to cannabis, tobacco, and other drugs. Importantly, this was not a conventional comparison between cannabis-exposed children and a healthy, drug-free control population. More than half of the “control” group classified as not exposed to cannabis or tobacco had been exposed to other substances.
The headline that ran for this study was “Prenatal Cannabis Exposure Not Associated With Cognitive Deficits in Toddlers.”
That's technically true, but it's missing an important detail. A more informative headline would be:
"Prenatal Cannabis Exposure Not Associated With Cognitive Deficits in Toddlers When Compared With Other High-Risk, Frequently Drug-Exposed Toddlers"
The cannabis-exposed kids scored about the same as, or even higher than, the other high-risk groups. The authors explicitly acknowledge that this does not mean the children were unaffected. They caution that cannabis exposure could still be associated with worse development than in the general population.
“...it is possible that cannabis exposure is associated with worse language development in the general population, even if we did not see this relationship in our sample of at-risk children.”
That's an enormous limitation if you're trying to use this study as evidence cannabis isn't harmful. If every group in your comparison may have developmental deficits or other unmeasured vulnerabilities, finding no difference between them doesn't establish that substance exposure is harmless.
Then, inexplicably, despite this limitation the authors conclude:
“This [finding] could help to reduce the stigma experienced by women who use cannabis during pregnancy and potentially lower the barrier for seeking help in this group.”
This study collected no data about stigma or barriers to seeking help. And its findings do not establish that prenatal cannabis exposure is harmless.
A Null Result Is Not a Safety Signal
If I look for evidence that cannabis causes X and don't find it, I have not necessarily demonstrated that cannabis is safe. I have demonstrated that I couldn't find evidence that cannabis causes X.
You cannot establish broad evidence of safety simply by collecting a long enough list of things that cannabis is not associated with.
The headline that ran for this study was “Prenatal Cannabis Exposure Not Associated With Negative Cognitive Outcomes at Adolescence.”
Taken narrowly, that's a reasonable description of the adjusted result. But this is a narrow finding focused on specific cognitive measures and, importantly, limited to what the researchers considered “low-level” prenatal exposure, reconstructed from parental questionnaires.
We don't have to attack the study itself. But we do have to recognize its limitations. Most importantly, we have to recognize the rhetorical conversion of a limited finding into a broader narrative that cannabis is safe, which this study cannot support.
A null result can be useful evidence. It is not permission to make a broader claim than the researchers actually tested. Failure to find one kind of harm is not the same as looking for any harm and finding none.
If these studies don't establish safety, what does the broader evidence actually say about cannabis during pregnancy?
Never Present Unfavorable Results
Even when the authors of a paper caution readers not to interpret their findings as evidence of safety, a headline and selective quoting can twist the meaning for most casual readers. Lies of omission are rarely exposed because most casual readers will never read the citations for themselves.
The headline that ran for this study was “In Utero Cannabis Exposure Not Associated With Later Developmental Delays.”
This is another rigorous study of a narrow outcome, performed well and published with appropriate caution. In this case, science communicators and advocacy groups carry the water by simply leaving out the authors' explicit cautions or downplaying them in the final write-up.
A direct quote from the research follows:
“Despite our findings… past evidence for adverse fetal and neonatal outcomes indicate… recommendations for pregnant individuals and those considering pregnancy to discontinue cannabis use should be followed.”
The authors support this discussion with 14 citations to the existing literature. Those citations form the foundation of our Cannabis and Pregnancy Research Review and demonstrate how two very different conclusions can be taken from the same paper depending on how broadly or narrowly the evidence is presented.
The narrow interpretation is true: this study did not find increased risk for the developmental delays it measured.
The broader interpretation is also important: the authors considered existing evidence and still recommended that pregnant people discontinue cannabis use.
Which version makes the headline depends on the story being told.
Learn More →
Cannabis and Pregnancy — Just Don't Do It
Cannabis and pregnancy is complicated only if you insist on having certainty.
There are legitimate studies finding no association between prenatal cannabis exposure and specific adverse outcomes. There are also innumerable legitimate concerns, important limitations to what we know, and enormous gaps in the evidence.
So our recommendation is simple: just don't do it.
That doesn't mean cannabis could never be medically appropriate during pregnancy. There may be circumstances where a patient and their healthcare provider decide the potential benefits justify the risks. That's a medical decision that should be made with an experienced healthcare provider who can help weigh those risks in the context of the individual patient.
But as a general rule, when the potential consequences involve fetal development, we don't need definitive proof of harm before exercising caution. That's what the precautionary principle is for.
But there is a larger lesson here.
Idea Laundering Does Not Require a Conspiracy
Nobody has to sit in a room and decide to deceive the public. People and organizations with similar incentives and an aptitude for reckless behavior can produce the same result through simple selective reading.
Favorable studies get promoted. Unfavorable studies don't. Useful quotations get repeated. Inconvenient qualifications disappear. Narrow findings presented en masse create a narrative totally unsupported by the evidence. Each person can accurately repeat something somebody before them said, and nobody ever has to invent a statistic or fabricate a study.
The research is real. The citations are real. The quotes are real. And the narrative is still bullshit.
Related Reading →
- Smoking is Not Wellness (Publishing Soon)
- Cannabis and Pregnancy - Research Review
- Why Doesn’t Modern Medicine Keep Us Healthy? (Publishing Soon)
