Cannabis Science, CBD

Smoking weed while pregnant: Is it dangerous?

pregnant woman

There are many different opinions about what is acceptable during pregnancy and what is not. Science has been able to give us more and more information about how certain substances harm fetuses. At this point, it’s widely understood that alcohol and cigarettes should be avoided during pregnancy but what about weed?

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Prevalence of smoking weed while pregnant

Are pregnant people using weed?  Yes. According to the American Congress of Obstetricians and Gynecologists (ACOG), it’s been self-reported that 2% to 5% of pregnant women use weed. This figure climbs when we begin to look at demographics. According to the study, the prevalence of weed use during pregnancy raises to 15–28% among young, urban, socioeconomically disadvantaged women. 

The study also points out that many marijuana users don’t stop during pregnancy. The study says “34–60% of marijuana users continue use during pregnancy”. There are two main reasons why.  Firstly, people have the belief that weed is pretty safe during pregnancy. Secondly, marijuana is less expensive than tobacco. 

Unfortunately, 18.1% of women who have used weed in pregnancy satisfied the criteria for either marijuana abuse, dependence, or both. 

Is smoking weed while pregnant safe?

The experts don’t believe it is. As a matter of fact, the experts don’t believe marijuana in any form is suitable for use during pregnancy. The Centers for Disease Control and Prevention (CDC) says “The chemicals in any form of marijuana may be bad for your baby – this includes eating or drinking, creams or lotions applied to skin, smoking, vaping and dabbing”. It’s recommended that women who are pregnant or who are trying to be pregnant abstain from using weed. 

The CDC believes that chemicals found in marijuana can be passed from mother to child and may cause negative outcomes. The article said, “Marijuana smoke has many of the same chemicals as tobacco smoke and may increase the chances for developmental problems in your baby”.

Limitations of the studies 

It’s difficult to know the exact reasons why marijuana during pregnancy isn’t safe. According to ACOG, “It is difficult to be certain about the specific effects of marijuana on pregnancy and the developing fetus, in part because those who use it often use other drugs as well, including tobacco, alcohol, or illicit drugs, and in part because of other potential confounding exposures.” The study went on to say factors such as poverty and malnutrition could be causing some of the issues that are being attributed to marijuana use. In addition to that domestic violence could be a reason why there are adverse outcomes. 

However, the study reassures that when the research into weed use pregnancy is being carried out, the confounders (like what’s listed above) are accounted for by using data stratification or multivariate analysis. In addition to that, the studies have limitations. According to ACOG, “Studies of marijuana exposure during pregnancy are potentially subject to reporting and recall bias, often relying on self-reported habits, including frequency, timing, and amount of marijuana use”

Is medical marijuana safe during pregnancy?

No. According to Healthline, even though people may want to use it to get rid of nausea and other pregnancy symptoms, it should be avoided.

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Is CBD safe for use during pregnancy?

No, CBD isn’t safe either. While a lot of the issues surrounding weed use and pregnancy are due to THC, CBD isn’t much better. According to the US Food and Drug Association (FDA), “High doses of CBD in pregnant test animals have caused problems with the reproductive system of developing male fetuses”. In addition to that, some CBD products may be contaminated with other substances. The FDA also warns that CBD may cause harmful interactions with drugs, liver toxicity, or extreme sleepiness. 

Are hemp seeds safe during pregnancy? 

Hemp is a cannabis plant known for its low levels of THC. The FDA says that hemp seeds should have low levels of THC and CBD especially compared to the leaves, flowers, and stem of the hemp plant. According to the FDA, “Hemp seeds can pick up miniscule amounts of THC and CBD from contact with other plant parts, but these amounts are low enough to not raise concerns for any group, including pregnant or breastfeeding mothers.”

Effects of smoking weed while pregnant 

There are a number of negative outcomes associated with smoking weed while pregnant. Healthline listed premature birth as an issue associated with smoking weed while pregnant. However, ACOG says that most reports do not show that link.

There are a couple of others negative outcomes that have come up in research such as:

Low birth weight 

According to the CDC, marijuana use during pregnancy could lead to low birth weight for babies. A study called Marijuana use and pregnancy: prevalence, associated characteristics, and birth outcomes was not able to find that birth weight was lower for marijuana users versus non-users. However, they did make mention of a larger study done in the Netherlands that found the opposite. The results of that study, according to this one are “decreased fetal growth with any exposure to marijuana, even in those who stopped use in early pregnancy, and what appeared to be a dose-dependent relationship with daily use leading to the lowest fetal weight”. 

In addition to that ACOG mentions that women using marijuana at least weekly during pregnancy were actually much more more likely to give birth to a newborn less than 2,500 g. The study mentions that other research has shown “smaller birth lengths and head circumferences as well as lower birth weights among exposed offspring” The researchers continue by saying “These findings were more pronounced among women who used more marijuana, particularly during the first and second trimesters”. However, they’re not sure of the clinical significance of this. 


According to ACOG, while perinatal death doesn’t seem to increase with marijuana use, the risk of stillbirth is. The study says, “Compared with nonusers, marijuana users experienced similar rates of perinatal death, but had somewhat higher stillbirth rates”. Even though the study didn’t account for tobacco use, THC is being associated with a stillbirth at or beyond 20 weeks of gestation. 

Affects brain development

ACOG made the point that endocannabinoids may be useful in normal brain development. The study says, “Human fetuses exhibit central nervous system cannabinoid receptor type 1 as early as 14 weeks of gestation, with increasing receptor density with advancing gestational age”. Exposure to foreign cannabinoids could harm brain development. 

In addition to that, there seem to be some lasting effects for children whose mothers used marijuana while pregnant with them. According to ACOG, “Studies noted that children who were exposed to marijuana in utero had lower scores on tests of visual problem solving, visual-motor coordination, and visual analysis than children who were not exposed to marijuana in utero”

Marijuana use during pregnancy is also linked to a decreased attention span and behavioral problems. It may even predict that a child will use marijuana by age 14. 


Scientists are still working to understand more about the dangers associated with using weed during pregnancy. However, the experts all agree that using weed in any form, except maybe hemp seeds, should be avoided during pregnancy.

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About Trevann

Trevann is Stoner Rotation’s Jamaica-based lead writer for the Science section of our cannabis blog. She graduated with honors receiving her Bachelor of Science degree in Molecular Biology from the University of West Indies, Mona. For the last three years, she has covered some of the biggest questions around cannabis and health underpinned with research from supporting studies, medical journals and scholarly articles. Got something on your mind? You can reach her at [email protected].

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