By Ryan Najjar

Pregnancy is an exciting and emotional experience, but regularly feeling ill is a part of the deal no matter what. You wake up queasy and stay that way for most of the day. It can be painful to even move!

Considering that, it makes sense that you'd want to grab your favourite strain, get some THC in your system, and smoke or vape your problems away.

You may want to rethink that move, however, as smoking weed while pregnant could cause your fetus to develop a variety of issues. There are a fair amount of studies that deny these risks, yes, but research confirming them is certainly worth considering.

What Are the Potential Risks of Smoking Cannabis While Pregnant?

  • Smoking cannabis while pregnant could lead to premature birth, low birth weight, small skull circumference, or neonatal death.
  • Rodent studies suggest the possibility of cognitive issues in children of mothers that used cannabis during pregnancy.
  • One should also consider the possible presence of other harmful substances like pesticides, mould, and bacteria that could harm the unborn child via the mother's consumption.

Risks of Cannabis Itself

What are the potential risks[1] of using cannabis while pregnant, anyhow? Well, there are a few, but doctors will mainly warn you about the possibility of your child having a low birth weight. Many also suggest a possible link between THC use and premature birth, and say it could even cause your child to have a small skull circumference when born.

Along with all that, as we'll further explain in a bit, rodent studies[2] have found that a mother using cannabis could lead to her child having cognitive issues further down the road. Of course, you'd need far more than animal studies to prove there's a true concern, but we can't definitively say there's no risk either.

The even more worrying idea, however, is the potential connection between sustained cannabis use during pregnancy and neonatal death. That issue, as we'll soon discuss, has some science to back it up, but we'll also show that it isn't quite set in stone yet.

Risks of Foreign Substances in Cannabis

Even in the event that THC is safe for consumption, you also have to account for what chemicals may be hiding in certain batches of bud or other THC-rich products. The industry is far from perfectly regulated, of course, and certain products could include anything from mould and bacteria to pesticides the plants were treated with during growth. Ingesting those sorts of substances would not only hurt you, but your child as well.

Risks of Foreign Substances in Cannabis

Cannabis and Pregnancy: What About CBD Oil?

  • CBD is usually framed as harmless, but early rodent studies show it may contribute to facial deformities in children whose mothers consume it.
  • Foreign contaminants, similar to those in THC-rich cannabis buds, could pass into the child during pregnancy (via the mother’s consumption), or afterwards (via the process of breastfeeding).

Risks of CBD Oil Itself

Let's be clear; up to this point, we've been referring to the use of THC-rich cannabis strains, as that's what's most popular these days. CBD oil, though, has been rapidly becoming more widely consumed.

Many users say it helps soothe their minds and their queasy stomachs, and it's perceived to be notably more safe than THC. Even then, though, we have to ask: is it safe to consume while pregnant?

As we'll soon detail, researchers have recently observed that CBD administered to rodent mothers caused their children to have facial malformations[3] in a fashion similar to fetal alcohol syndrome. Problems don't stop in the womb either, as other animal studies have shown that a child could possibly ingest CBD via their mother’s breast milk. The CBD in there wouldn't necessarily cause problems, although it isn't risk-free, either.

Risks of Foreign Substances in CBD Oil

Besides that, there's no telling what's in some CBD products these days. There's CBD in there, sure, but many manufacturers aren't careful about contaminants, leading to substances like bacteria and pesticides ending up in batches of oil and other products. Ingesting those, of course, would definitely lead to problems, whether it's your fetus or breastfeeding child.

Some Research Confirms Risks of Cannabis Use During Pregnancy

  • A study looking at 314 pregnant cannabis users and 4,700+ pregnant non-users found the former group to have children with lower birth weights than those from the latter group.
  • There was also a higher rate of premature birth in cannabis users than non-users.
  • That study is marred by a disproportionately large control group. A study with 5,000 pregnant users and 5,000 pregnant non-users, for example, would be more reliable.
  • A rodent study administered CBD oil to pregnant subjects and found the children to sustain facial deformities. This doesn’t confirm the effect in humans, but further research is needed.

Low Birth Weight and Premature Birth Risk

While some cannabis supporters will say there's no connection between cannabis and pregnancy issues[4], a study released in 2020 says otherwise. Researchers from around the UK observed over 5,000 pregnant women, dividing them into five groups: those who never used cannabis, those who only used it before pregnancy, those who stopped using it right before, those who used it but stopped before the 15-week mark, and those who used it after 15 weeks.

Observing these groups through pregnancy and birth, researchers found the children of mothers who smoked after 15 weeks to have a lower mean value birth weight and a greater chance of premature birth. However, if the women stopped using cannabis before the 15-week mark, their children's outcomes were not much different from those with mothers who never used it.

The large sample size is a good sign for the validity of this study, but it's worth noting that the women were not split into evenly sized groups. Of the 5,000+ women in the study, only 314 were noted to have smoked cannabis in any capacity. That's still more people than we usually see in any study on cannabis, but a 4,700+ person control group is excessive, and the overall size of this study could mislead someone into thinking it's more representative than it actually is.

Low Birth Weight and Premature Birth Risk

Early Research on CBD Hints at Further Complications

Another study, released in late 2019[5], focused on CBD and the effects it could have on pregnant rodents and their children. Comparing their observations with neonatal rodents with fetal alcohol syndrome, researchers found those rats, and the ones with CBD-treated mothers, to suffer similar facial deformities. These results don't confirm what would happen in humans, of course, but they could be considered a fair reason for mothers to proceed with caution.

Some Research Denies Risks of Cannabis Use During Pregnancy

  • A review of 184 studies on cannabis and pregnancy suggests that few connections have actually been found between cannabis use in pregnant humans and the health of their children.
  • The most recent study reviewed is from 2017, so it doesn’t include the ones we just discussed, but it’s worth noting how the studies they reviewed failed to account for confounding factors like finances, health, and education.
  • This doesn’t necessarily mean there’s no risk, but it means more research is needed before anything can be said for sure.

Research Review Denies Connections Between Cannabis and Pregnancy Issues

If you consider other equally recent and valid studies, however, you could also argue there is insufficient evidence to claim cannabis use during pregnancy is wholly unsafe either. Researchers at NYC's Columbia University, the New York State Psychiatric Institute, and Australia's Swinburne University looked at 184 studies[6] dating up to December 2017, the combination of which describes 1,000+ subjects between 0 and 22 years of age.

The researchers noticed that cannabis use in pregnant mothers had few connections to the issues or positive characteristics of their newborn children. They also noted that some of the studies that did show differences failed to account for the economic situation of the parents or children, their access to education, or other aspects of their health.

In turn, we should take these studies with a grain of salt when they claim cannabis itself causes birth defects and other issues later on. On the other hand, though, it also means that other studies with these oversights need to be reconsidered as well.

More, and Better, Research Is Needed

So, rather than making a statement on the lack of risks, this review of studies could be considered a call for future research to more carefully consider confounding factors. More specifically, researchers need to ensure they're not just observing one socioeconomic group per study, and that their subject pools are not only large, but fully representative of the communities they come from.

Consider Quitting Cannabis to Be Safe During (And After) Pregnancy

  • Until more substantial research comes out denying the risks, it may be safer to avoid using cannabis during pregnancy.
  • Considering how substances a mother uses can pass on to her child via breastfeeding, it could be wise to avoid using cannabis during that time period as well.
  • However, don’t think of it as quitting! Frame it in your mind as a tolerance break. Once your child is done breastfeeding, you can (responsibly) enjoy as much cannabis as you’d like.

Think of It as a Tolerance Break

Now, we understand the idea of quitting may bum you out. After all, we’re sure you’ve had great times with cannabis, and we get that it can bring you a lot of relief in stressful times.

All stoners take tolerance breaks, and the longer ones result in weed hitting you as hard as it did the first time you ever smoked. With that mindset, you’re no longer “quitting”, but instead saving it to fully enjoy after giving birth and breastfeeding.

Above all, if you still think you'll need it while pregnant, especially if you're a medical cannabis patient, just be sure to speak to your doctor about an ideal treatment plan. That goes for people who use CBD oil as well! Only use verified, trustworthy CBD products, and have a conversation with your doctor before taking it during pregnancy.

External Resources:
  1. Can marijuana use during and after pregnancy harm the baby? | National Institute on Drug Abuse (NIDA)
  2. How Marijuana Use During Pregnancy Could Harm a Developing Baby's Brain - Scientific American
  3. Cannabinoids Exacerbate Alcohol Teratogenesis by a CB1-Hedgehog Interaction | Scientific Reports
  4. The deleterious effects of cannabis during pregnancy on neonatal outcomes | The Medical Journal of Australia
  5. Cannabinoids Exacerbate Alcohol Teratogenesis by a CB1-Hedgehog Interaction | Scientific Reports
  6. Frontiers | Totality of the Evidence Suggests Prenatal Cannabis Exposure Does Not Lead to Cognitive Impairments: A Systematic and Critical Review | Psychology
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

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