Cannabis use during pregnancy

Cannabis use during pregnancy
Cannabis use is not recommended during pregnancy. Here’s why.

Is it dangerous to use cannabis during pregnancy? Here are the answers to some common questions about cannabis use and pregnancy.

What are the effects of cannabis during pregnancy?

According to the most recent Canadian statistics, it’s estimated that 3 to 5 percent of pregnant women and 3 to 6 percent of breastfeeding women use cannabis. Cannabis is the most widely consumed substance during pregnancy after alcohol.

When a pregnant woman uses cannabis, she also exposes her unborn baby to the drug. That’s because THC, the chemical responsible for most of cannabis’s psychoactive effects, is able to cross the placental barrier.

A number of studies have explored the effects of cannabis on fetal development, but results vary from study to study and may be influenced by the use of other substances, such as tobacco.

We do know that mothers who regularly use cannabis during pregnancy are at greater risk of having a premature or low-birth-weight baby or having their child admitted to the neonatal intensive care unit.

What’s more, some studies have shown that exposure to cannabis before birth may affect children’s cognitive and behavioural development. For example, children exposed to cannabis in the womb may exhibit more hyperactive behaviour, impulsivity, or reading difficulties in childhood. However, this does not mean that THC exposure during pregnancy causes ADHD.

Health professionals recommend caution and advise pregnant women to avoid cannabis use.

Should I be worried if I used cannabis before I knew I was pregnant?

There is no precise data on how long a person should abstain from cannabis use before becoming pregnant. Since you can’t predict exactly when you’ll conceive, it’s best to stop using cannabis altogether if you’re trying to get pregnant.

It’s especially important to stop using cannabis as soon as you know you’re pregnant and to discuss your cannabis use with the professional monitoring your pregnancy.

If it’s not possible for you to stop using cannabis completely, it’s best to cut back as much as possible, as there appears to be a correlation between the amount of cannabis consumed, the frequency of use, and the risk to the unborn baby.

What about edible cannabis products?

It is not recommended to consume cannabis oil or edibles if you’re pregnant. No matter how you use or ingest cannabis, the THC it contains will still be able to cross the placental barrier, and your baby will be exposed to its effects. Cannabis-containing products may also have an impact, although they have not been studied as extensively.

Can my partner or friends smoke cannabis around me?

Those around you should always step outside if they want to smoke. They should never smoke while in the car with you. As with tobacco smoke, secondhand cannabis smoke can be bad for your unborn baby’s health, and for yours. It can also be harmful to newborn babies.

Is occasional cannabis use risky?

The Society of Obstetricians and Gynaecologists of Canada reports that 70 percent of pregnant and non-pregnant women believe there is a slight or no risk of harm from using cannabis occasionally (i.e., once or twice a week) during pregnancy.

However, there is no data to support the view that occasional cannabis use is risk-free for the mother and unborn baby. Ideally, all cannabis use should be avoided during pregnancy.

I only use cannabis to relieve my nausea. Is that okay?

Given the risks to you and your unborn baby, the use of cannabis to relieve nausea and other pregnancy-related discomforts is not recommended. It’s best to talk to your prenatal care provider. They’ll be able to find safer pharmacological and non-pharmacological alternatives to relieve your symptoms.

Should I talk to a health care professional about my cannabis use?

Yes, don’t hesitate to speak to your prenatal care provider. A doctor, nurse, or midwife can monitor your pregnancy and give you the support you need. Having an honest conversation is the first step in finding a solution that’s right for you.

What should I do if I want to stop using cannabis?

Your prenatal care provider can help. If necessary, they can refer you to local resources to help you through this process. You can also contact your CLSC or specialized addiction resources in your region.

What about other drugs?

All drugs can pass through the placenta and potentially interfere with the course of pregnancy and fetal development. These include cocaine (crack, coke), hallucinogens (LSD, mushrooms, etc.), solvents, ecstasy, amphetamines (crystal, speed), methamphetamines (ice, meth), and opiates (heroin, morphine, etc.).
Some of these drugs can also cause the baby to experience withdrawal after birth. Symptoms may include inconsolable crying, irritability, trembling, and feeding difficulties. What’s more, some drugs can have long-term effects on the infant.
If you use drugs, it’s important to talk to a health professional about it. They can offer support and ensure you have a healthy pregnancy. If you want to stop using, they can also direct you to the right resources.

Things to keep in mind

  • Pregnant women should not use cannabis. If quitting altogether isn’t an option, it’s best to cut back as much as possible.
  • Pregnant women should not be exposed to secondhand cannabis smoke.
  • Pregnant women who use cannabis should talk about it with their prenatal care providers.


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Naître et grandir

Scientific review: Dr. Louis-Xavier D’Aoust, Family Doctor, CIUSSS Centre-Sud-de-l’Île-de-Montréal and Assistant Clinical Professor, Université de Montréal Faculty of Medicine
Research and copywriting: The Naître et grandir team
Updated: December 2023

Photo: GettyImages/nd3000

Sources and references

Note: The links to other websites are not updated regularly, and some URLs may have changed since publication. If a link is no longer valid, please use search engines to find the relevant information.

  • Canadian Centre on Substance Use and Addiction. “Is it OK to use cannabis during pregnancy and while breastfeeding?” 2022.
  • Canadian Centre on Substance Use and Addiction. Clearing the Smoke on Cannabis: Cannabis Use during Pregnancy and Breastfeeding. 2022.
  • CHU Sainte-Justine. “Ouf la nausée! Le menu des options.” 2023.
  • CHU Sainte-Justine. Cannabis, grossesse et allaitement. 2020.
  • Doré, Nicole, and Danielle Le Hénaff. From Tiny Tot to Toddler: A practical guide for parents from pregnancy to age two. “Cannabis and other drugs.” Quebec City, Institut national de santé publique du Québec. 2023.
  • Drugs: Help and Referral. “Cannabis.”
  • Giguère, Ugo. “Des femmes ignorent les risques associés au cannabis durant la grossesse.” 2023.
  • Hayer, Sarena, et al. “Cannabis and pregnancy: A review.” Obstetrical & Gynecological Survey, vol. 78, no. 7, 2023, pp. 411–428.
  • Radio-Canada. “Montée de problèmes liés à la consommation de cannabis chez les femmes enceintes.” 2023.
  • Health Canada. “Thinking about using cannabis before or during pregnancy?” 2018.
  • Health Canada. “Substance use.” 2023.
  • The Society of Obstetricians and Gynaecologists of Canada. Pregnancy Info. “Substance use in pregnancy.”
  • The Society of Obstetricians and Gynaecologists of Canada. Pregnancy Info. “Are you pregnant, considering pregnancy, or breastfeeding? Do you know that the use of cannabis may not be safe for your baby?”
  • Sorkhou, Maryam, et al. “Birth, cognitive and behavioral effects of intrauterine cannabis exposure in infants and children: A systematic review and meta-analysis.” Addiction, vol. 119, no. 3, 2024, pp. 411–437.
  • Université Laval. “Grossesse et cannabis : quels effets sur l’enfant?” 2023.