What We Do and Don’t Know About the Safety of Marijuana During Pregnancy
Marijuana has a healthier lifestyle than many other drugs (or, depending on who you ask, alcohol), and it can relieve symptoms such as nausea that commonly occur during pregnancy. But we are accumulating evidence that marijuana is probably not the best option for pregnant women. Specifically, the THC component can affect a child’s brain in ways that you might not notice until they get older.
If you are looking for a simple yes / no answer about whether cannabis can be used during pregnancy, I will point you to this definitive “no” by the American Congress of Obstetricians and Gynecologists . “While there are limitations on data on marijuana use during pregnancy … alarming trends are emerging,” they write. Children who are exposed to marijuana in the womb are more prone to cognitive and behavioral problems later in life. The experts I spoke with strongly discouraged smoking weed while pregnant. If you want yes or no, here’s your no.
But you are probably reading this because you want to know why this is negative, how strong the evidence is, and if there is room for wiggle room in your situation. So here are the details.
Marijuana affects brain development
The most famous chemical in marijuana is tetrahydrocannabinol (THC). This is the main psychoactive component, the part that gets you high. THC circulates in your blood and can cross the placenta, so the fetus is exposed to it too. THC is also fat soluble and can end up in body fat. This means that a small amount of THC may still be circulating in your body, even if you have not used marijuana recently.
THC can also pass into breast milk and its metabolites pass into your baby’s feces , so if you use marijuana and are breastfeeding, your baby is also exposed to this chemical.
Some of what we know about the biology of marijuana comes from studies in which scientists gave pure THC to animals like rats. Diane Doe-Edwards , who is researching how drugs affect the developing brain in animals, says it’s well known that THC affects how brain cells connect to each other. “This is, of course, the whole point of the brain,” she says. “One neuron connects to the next neuron, which connects to the next.” And the more marijuana is exposed to the brain, the stronger the effect on these connections.
Human brain cells develop in a similar way to rodent cells, but we need real research to understand what this means for us. Conducting a randomized controlled trial is unethical because it would require some women to prescribe marijuana during pregnancy. So instead, studies look at the children of people who choose to use marijuana on their own during pregnancy and try to find out if these children have more problems than children whose mothers did not use marijuana.
Dow-Edwards notes that only two of these studies tracked babies for decades after birth and took into account factors that might otherwise influence the results. These are the Ottawa Prospective Study of Prenatal Age, begun in 1978, and the study of the practice of maternal health and child development, begun in 1982.
The results of both studies showed that pregnancy and childbirth proceeded more or less as usual, but as children got older, they were more likely to have problems with memory, attention and hyperactivity.
But what about other studies?
The evidence from these long-term studies, as well as what we know in animals, definitely indicates that cannabis has deleterious effects on children’s brains. But there has been enough research done on the effects of marijuana on pregnancy, so it’s easy to pick a few with the opposite conclusion.
Marijuana-friendly publications tend to ignore the aforementioned studies and instead prefer others like this one conducted in Jamaica . I asked Dow-Edwards how these studies fit into a broader set of studies, and she pointed out that Jamaican mothers and the way they use marijuana are different from those you find in the US or Canadian populations. In Jamaica, ganja is often consumed as a tea, and this tea contains mostly cannabidiol (CBD) and very little THC. The Jamaican studies were also small and did not track infant growth.
Another short-term study with seemingly good results is a systematic review that examined whether marijuana promoted early or small childbirth. It concluded that “use of marijuana during pregnancy is not an independent risk factor for adverse newborn outcomes [].” Herb summed it up as follows: “New research says smoking cannabis during pregnancy is normal if it is moderately “, which is not true. everything that the study says.
In fact, the study authors concluded that while marijuana is not as harmful to newborns as other drugs, “these findings do not mean that marijuana use during pregnancy should be encouraged or tolerated.” The potty may not harm newborns in obvious ways, but the long-term effects seem to be serious.
Summary of Colorado Testimonies
If only someone could take apart all the studies, short and long term, that offered information on the effects of prenatal marijuana on children’s health. If only that someone was from a relatively unbiased source like the state health department, which permits both medical and recreational marijuana. It would be nice, right?
You can thank the Colorado Retail Marijuana Public Health Advisory Committee for its annual report on the science behind health and marijuana . The chapter on pregnancy and breastfeeding breaks down what we know based on how strong the evidence is. There are no findings that have what they called substantial scientific support, but some of them fall into the category of moderate evidence, which they define as meaning “scientific evidence supports a link between marijuana use and outcome, but these findings have some limitations. “. In other words, the evidence is pretty good, but not ironclad. These include:
- Attention problems
- Decreased IQ scores in young children
- Decreased cognitive function
- Decreased growth
Then there are some results with limited evidence, which means the studies support the link, but the studies have “significant limitations.” Some of them may turn out to be happy accidents, but, again, they may be real:
- Stillbirth
- Certain heart defects
- Decreased academic ability
- Increased symptoms of depression
- Delinquent behavior
This category of evidence also contains good news: there is limited evidence that prenatal marijuana use is not associated with SIDS.
In the next category, there is insufficient evidence to link marijuana use during pregnancy with symptoms of psychosis during adolescence, or with an increased likelihood that a baby will grow up and be more likely to use marijuana on its own. There is also insufficient data to link the use of marijuana while breastfeeding to SIDS.
Finally, there is another category of mixed evidence, which means that some studies say yes and others no. Most birth outcomes (premature birth, low birth weight) fall into this category. You can view the full report to see what studies the advisory committee used and how they analyzed them.
Not all weeds are the same
Why do all these studies come to different conclusions? Aside from the complexity of doing the research (and getting women to admit they used marijuana during pregnancy), there is much more that the researchers call dubious . If you use marijuana during pregnancy, you are probably not the type to go cold turkey with cigarettes and alcohol. You may be of a different age or income level than moms who have quit smoking or have never started. And then there’s the question of the weed itself.
When these two long-term studies began, the marijuana you bought on the street contained about 3 percent THC. Today’s cannabis is stronger: 8 percent or more for similar products, and more concentrated products like hashish can contain 20 to 30 percent THC. So it is possible that using marijuana during pregnancy is more harmful today than it was in the 1980s.
There are also many options for using marijuana. How often do you use it? Do you smoke it, vape it, or eat it? How far is your pregnancy? (Different parts of the brain and nervous system mature at different times. In fact, brain development isn’t complete until you’re in your twenties, which means teenagers probably shouldn’t smoke weed either.)
Marijuana also contains dozens of psychoactive substances, of which THC is the most studied. We know very little about what others are doing. Cannabidiol, or CBD, is another compound that has been credited with many of the drug’s medicinal effects, but we don’t know as much about it as we would like.
Some strains of cannabis claim to be low in THC and higher in CBD, which sounds like it should be safer, but you can’t always trust the labels . Dr. Larry Walk, head of the Colorado Department of Public Health, says potency testing isn’t always accurate enough to guarantee exactly what you get. “It’s hard to make any medical statement about [all] marijuana,” he says. “It’s so patchy. This doesn’t sound like a medical statement about ibuprofen. “
One final word of caution about foods high in CBD: Dow-Edwards notes that “There have been no human studies with CBD during fetal development. No one.”
Risk and benefit
If marijuana has these risks, or even potential risks during pregnancy, it seems logical not to smoke it. But women use marijuana in about 5% of pregnancies . Many people use it to treat nausea. And anyone living through the hellish months known as pregnancy hyperemesis must seriously calculate the risk-benefit ratio. Here is one woman describing her situation for Vice :
The medical term for what I have suffered is pregnancy hyperemesis, which is a bizarre way of saying that I was vomiting so badly that it was dangerous for my health and that of my baby. Marijuana has really helped. Immensely. I don’t think I would have survived without cannabis.
However, overuse of marijuana can also cause its own hyperemesis syndrome , so more marijuana doesn’t always mean less nausea.
Whether you have to choose between a potentially harmful IQ or your unborn baby’s attention, or perhaps not survive a pregnancy, this is a difficult decision that you must work with a trusted doctor or provider. But Doe-Edwards says she met people who said their doctor told them that marijuana was safer than drinking. “It’s just not true,” she says. Therefore, it is important to make sure your supplier understands the benefits and risks.
What we still don’t know
We don’t know if the effects of marijuana in the two long-term studies will differ from today’s marijuana.
We don’t know if there are other effects of marijuana that haven’t been studied yet. It is difficult to get approval for human studies, and it would be completely unethical to compare marijuana to placebo in pregnant women.
The Colorado report points out that since marijuana was banned throughout the US until 1996, most studies looked for harm rather than trying to thoroughly figure out the benefits or trade-offs. “This … introduces bias in both funding and publications in the literature related to marijuana use,” the report notes.
We cannot go back in time to resume long-term learning, but we can support better research now. Dr. Walk hopes that over time, Colorado and other state health departments will keep careful records of who uses marijuana during pregnancy and what complications they or their children have. This is not the case yet.
Finally, we need more data on everything, especially CBD and the 80+ other active ingredients in marijuana besides THC. We also don’t even know all the questions we should be asking. Doe Edwards notes that five years ago, we didn’t know if smoking marijuana could cause lung cancer; now we are almost certain that it is . There is still a lot we don’t know.