Last updated Dec. 28, 2017.
Marijuana has gone through a lot of ups and downs in public opinion in the past 100-odd years and it’s currently experiencing a serious upswing. Seven states and Washington, D.C. have legalized it for recreational use and 29 more states have legalized it for medical use. Almost half of Americans admit to having tried pot at least once in their lives, and just over 1 in 10 say they’ve smoked within the past year. That makes it the most commonly used illegal drug in the U.S.
There’s plenty of debate about the health effects of marijuana in general, but how does it affect mothers-to-be? We know that many things you put into your body while pregnant can affect the baby, so what’s the deal with marijuana and pregnancy?
How Marijuana Affects the Body
To get a sense of the effects of smoking weed during pregnancy, we first need to take a look at how it affects the body in general. The main psychoactive component in pot is delta-9-tetrahydrocannibinol, usually abbreviated to “THC.” When you take in THC (usually by smoking, although you can also “vape” or eat it), the chemical binds with certain receptors in the areas of your brain responsible for coordination and memory, among others. Those receptors typically bind with anandamide, a cannabinoid naturally produced by your body that is responsible for a variety of immune and neurological functions.
When THC binds with your cannabinoid receptors, it can cause a loss of coordination and short-term memory problems. This same reaction causes the feelings of euphoria we typically associate with pot use. Smoking weed can also increase your heart rate and cause anxiety and paranoia.
Compared to other drugs, including alcohol and tobacco, marijuana is not highly addictive. However, it can be psychologically habit-forming and regular users may experience irritability and anxiety if they stop using the drug. While marijuana smoke contains many of the same chemicals and irritants found in tobacco smoke, the link between weed and an increased risk of lung cancer is unclear. A 2012 study of over 5,000 participants found that occasional pot smoking caused no adverse effects on the lungs, although heavy smokers are prone to inflammation of the airways, leading to coughing and wheezing. Finally, marijuana cannot cause death by overdose.
Is marijuana safe during pregnancy?
What’s the motivation for smoking pot while pregnant? First off, expectant mothers may have already been using marijuana and simply enjoy it. But other mothers struggle with chronic pain or morning sickness and may be considering marijuana as an alternative to other medications. Many painkillers have proven to be unsafe during pregnancy, meaning women have limited options for dealing with pain for those 40 weeks. Severe morning sickness can be debilitating, and marijuana’s anti-nausea and appetite-boosting effects are well-established (hence its popularity among chemo patients).
So, is it safe?
The answer is that we just don’t know. The American Congress of Obstetricians and Gynecologists (ACOG) recommends against the use of marijuana during pregnancy, but notes that it is “difficult to be certain about the specific effects of marijuana on pregnancy and the developing fetus.” In part, they say, that’s because there are no good studies on the effects of smoking pot while pregnant. There are obvious ethical problems with setting up controlled studies and deliberately exposing fetuses to marijuana. Studies of the children of women who report smoking weed during pregnancy have produced mixed results, since it is difficult to separate the effects of smoking marijuana from socioeconomic factors such as malnutrition, poor prenatal care, smoking tobacco, and the effects of other substance use (lower-income women use marijuana much more frequently than higher-income women and are at higher risks for all of those factors).
That said, some studies have found that children exposed to marijuana in the womb showed signs of delayed neurological development, weaker problem-solving skills, and poorer motor control compared to children that were not exposed. Another study indicated that children exposed prenatally to marijuana were more prone to attention-deficit problems. However, a different study found no link between prenatal marijuana exposure and school performance. Studies have produced conflicting evidence on whether marijuana use contributes to low birth weight or the risk of birth defects, according to ACOG.
Essentially, the waters are murky. We know that endocannabinol receptors (the ones that bind with THC) have proven important for the neurological development of fetuses in animal studies, and exposure to the cannabinoids in THC can affect those receptors negatively. However, animal studies aren’t always a clear match for human studies and there simply isn’t much research on the role of endocannabinol receptors in human development.
That said, the most recent research seems to suggest that marijuana is not, in fact, linked to preterm birth or low birth weight. A study from the Washington School of Medicine, published in Obstetrics & Gynecology in September 2016, originally did find a link between marijuana and those problems. However, that increased risk went away when they accounted for whether the mothers smoked tobacco as well as marijuana. People who smoke pot are more likely to also smoke tobacco, which is clearly linked to preterm birth and low birth rate, so the researchers suggest that earlier studies were not taking tobacco use into account.
They also note, however, that this study didn’t examine the long-term effects of marijuana use and does not include any findings on the possibility that marijuana may affect fetal brain development.
Marijuana and Pregnancy: The Bottom Line
So, smoking pot while pregnant hasn’t been definitely proven unsafe for you or the baby. However, it also hasn’t been proven safe, and some studies do suggest that there may be risks associated with using marijuana during pregnancy. At the end of the day, you’ll need to be open with your doctor about whether you currently use marijuana or are considering it during your pregnancy. You and your doctor can work together to evaluate the risks and decide whether marijuana and pregnancy fit together for you. The answer may depend in part on the frequency and purpose of use. If you’re looking for treatment for morning sickness or anxiety, for example, there are other FDA-approved treatments that may work for you.
You should note that in some states, smoking pot while pregnant may be considered a criminal offense under certain child abuse laws and may result in the involvement of Child Protective Services. Before considering marijuana use, you should check out the laws in your state to determine whether that’s a risk.