Cannabis (Marijuana)

Last Update: 08 Jan 2026

Medication

Table of content

1. What Is It? 2. Risks 3. Benefits 4. Lactation 5. Key Takeaways 6. Research limits

Welcome to our Fact Sheet on cannabis and related compounds during pregnancy and lactating. The information given is based on current research and may be updated with new scientific knowledge. This information does not replace personalized advice from healthcare professionals.

1. What Are Cannabis, Marijuana, THC, and CBD?

Cannabis, also known as pot or marijuana, is a plant that can be used in different forms, such as smoking, vaping, oils, or edibles. It contains many active substances including:

Δ9 -tetrahydrocannabinol (THC): the main compound responsible for the “high” or psychoactive effects.
Cannabidiol (CBD): compound often used for calming or pain-relieving effects, but without the same “high” as THC.

The amount of THC or CBD can vary widely between products, and even CBD products labeled as “THC free” may still contain small amount of THC.

In addition to recreational use, cannabis and related products are sometimes prescribed for medical reasons, such as pain, nausea, or other conditions. However, this does not mean cannabis is considered safe in pregnancy or during lactation.

These compounds act on the body’s endocannabinoid system, which plays a role in reproduction, implantation, and the baby’s development during pregnancy. In Canada, cannabis is legal for recreational use. However, both Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend that pregnant and lactating people avoid cannabis use, whether for recreational or medical reasons, unless advised otherwise by a qualified healthcare provider.

It is important to let your healthcare provider know if you or your partner use cannabis and you are planning a pregnancy, are currently pregnant, or are lactating. This information helps them give you clear information about the risks and support you in choosing the safest options for you and your baby.

Tip: If you need help reducing or stopping cannabis use, remember you are not alone. Talk to your healthcare professional about the support services available in your area.

2. Why Is It Important to Talk About Cannabis Use During Pregnancy?

Cannabis is the most commonly used substance during pregnancy after alcohol and tobacco.

In Canada, about 2 to 4 out of every 100 pregnant people report using cannabis during pregnancy. Some pregnant people use cannabis to help with nausea, anxiety, sleep problems, or pain, even though cannabis has not been proven safe to use during pregnancy.

Some people choose cannabis because it is legal or seen as “natural”, and they may feel it is safer than some prescribed medications. However, “natural” does not always mean safe, especially during pregnancy, because a baby is still developing.

Health professionals do not always ask about cannabis use. One study found that many pregnant people (37%) were never asked, and more than half (62%) did not receive clear advice to avoid cannabis during pregnancy.

Even though cannabis is legal and sometimes viewed as a low-risk product, the science is still incomplete and often uncertain. This is why open and respectful conversations about cannabis and pregnancy are important.

Understanding the Risks during Pregnancy

Every pregnancy carries what is called a background risk. This means complications like miscarriages (loss of the pregnancy), birth defect (malformation present at birth), premature birth (born before 37 weeks), and other complications can happen in any pregnancy for many reasons. Research helps understand whether cannabis use may add to these risks.

So far, studies have found that cannabis use during pregnancy may:

Increase the chance of having a low birth weight (less than 5 pounds and 8 ounces [2 500 grammes] or preterm birth (born before 37 weeks).
Be linked to a higher chance of difference in the baby’s brain development, which could affect attention, memory, and learning later in life.
Possibly raise the chance of having a stillbirth, although more research is needed.

Research on cannabis in pregnancy is still limited. Most studies rely on people reporting their own use, which may not always be accurate. It can also be difficult to separate the effects of cannabis from other factors, such as tobacco or alcohol use. In addition, the amount, form (smoking, edibles, oils), and strength of cannabis products can vary widely. Moreover, the ingredients present in cannabis products are not always well controlled, and they may contain substances whose risks are not fully known.

This means we know cannabis use during pregnancy carries risks, but we do not know exactly how big those risks are or how it may affect each pregnancy and baby. Because of these uncertainties, Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend avoiding cannabis use during pregnancy.

The table below summarises what research has found so far. These risks are relatives (they compare people who use cannabis to those who do not). Other factors like age, genetics, habits, or other medical conditions can also influence your personal risk.

Table 1. Risks associated with cannabis use in pregnancy.

Who?	What?	What does research say?
Pregnant person	Fertility	Cannabis may affect hormones and ovulation (the release of an egg). Some studies found it could make it harder to get pregnant, but not all studies agree.
	Miscarriages	Some studies found a slightly higher chance of miscarriage. Other studies have not confirmed this risk.
	Pregnancy complications	Cannabis use has been linked to a higher chance of high blood pressure and other complications. Smoking cannabis can increase carbon monoxide levels in the blood. This may lower the amount of oxygen reaching the baby.
For the unborn child	Congenital Malformations	A large Canadian study found a higher chance, but other studies did not confirm this.
	Growth	A 2025 systematic review found a consistent link between cannabis exposure and low birth weight. The chance of being small for gestational age may be 1.5 to 2 times higher compared to babies not exposed to cannabis.
	Premature Birth	Findings are mixed. Some studies show a slightly higher chance while others do not show a clear increase.
	Neonatal health	Some studies found a higher chance that newborns exposed to cannabis may be admitted to the neonatal intensive care unit (NICU).
	Stillbirth	Some large Canadian studies found a higher chance of stillbirth, but more research is still needed.
Child later in life	Brain development	Some studies found a higher chance of attention, memory, and behavioral difficulties later in life. Studies also report a higher chance of learning difficulties, attention problems, and impulsivity.
Child later in life	Mental health	Some studies found a higher chance of anxiety or psychosis-related symptoms during adolescence.
Fathers or sperm donors	Fertility and conception	Regular cannabis use can lower sperm count, sperm quality, and sperm movement (motility). Some studies link cannabis use to male infertility. No direct effects on infant health have been shown, but it may reduce the chance of conception.

3. Are There Any Benefits of Cannabis in Pregnancy?

Research does not show clear, reliable benefits of using cannabis during pregnancy. Some people use cannabis to try to ease nausea, anxiety, or pain. However, studies in pregnant people have not proven cannabis use is effective or safe during pregnancy, and there may be risks for the baby. Because of this, major health groups recommend avoiding cannabis during pregnancy.

If you’re looking for relief, there are adapted, evidence-based options. More information can be found in the related factsheets.

Nausea and vomiting: Some non-medical options may help like eating small, frequent meals; ginger; or acupressure. There are also pregnancy-safe medications that may help, such as Diclectin® (doxylamine-pyridoxine).
Anxiety and sleep: Relaxation techniques, breathing exercises, cognitive-behavioral therapy (CBT), and sleep routines can help. If symptoms are strong or hard to manage, a healthcare provider can recommend or prescribe other options.
Pain: It may help to start with approaches like rest, gentle stretching, physiotherapy, or heat/ice. In some cases, acetaminophen (e.g. Tylenol®) may be appropriate. Ongoing or severe pain should always be discussed with a healthcare provider.

If symptoms are hard to manage, talk to your healthcare provider. They can help you find safer treatments for you and your baby.

Nausea can be challenging during pregnancy, here's a few tips to help.

Learn more

4. Will I Be Able to Breastfeed/ chestfeed?

Current research shows that THC passes into breast milk. THC can stay in the lactating person and in a baby’s bodies for several days.

Cannabis and secondary smoke can have an impact on the baby’s health. This means a baby may still be exposed even if cannabis is not used every day. Reported risks for babies include changes in sucking behavior, increased sleepiness (sedation), and possible effects on brain development.

Because of these risks, Health Canada and other health authorities recommend avoiding completely cannabis while lactating.

Lactating and feeding choices are personal. If you have questions about your situation, it’s best to speak with your healthcare professional (doctor, nurse, pharmacist) or a lactation consultant. They can help you explore the options for you and your baby, without judgment.

Key Takeaways

Cannabis, also known as marijuana, is a plant that contains many active substances including THC and CBD.
Health Canada and the Society of Obstetricians and Gynaecologists of Canada recommend avoiding cannabis use during pregnancy.
Cannabis use in pregnancy is linked to risks like low birth weight, preterm birth, stillbirth, and possible effects on brain development later in life.
THC passes into breast milk and can remain in the lactating and baby’s bodies for several days, this is why Health Canada and other health authorities recommend avoiding completely cannabis while lactating.
If you use cannabis to cope with symptoms like nausea, anxiety, or pain, talk to your healthcare team — safer, evidence-based alternatives are available.

6. Research Is Great, But It Is Not Perfect

Making informed decisions also means understanding both what studies can tell us and where uncertainties remain. Current research on cannabis in pregnancy has several limitations:

Observational studies: Most studies are observational. They show patterns and associations but cannot prove cannabis directly causes certain outcomes. Other factors may also play a role.
Unclear amount, form, and timing: Studies do not always report how much cannabis was used, what form (smoking, vaping, oils, edibles), or at what stage of pregnancy. These differences can affect risks.
Limited knowledge about CBD: While THC is the main psychoactive compound, the role of CBD in pregnancy is still uncertain. More research is needed to understand its effects.
Use of other substances: Many people who use cannabis may also use alcohol, tobacco, or other substances, making it harder to separate the specific effects of cannabis.

Because of these limitations, results should be interpreted with caution. Until stronger evidence is available, it is recommended to avoid cannabis during pregnancy and breastfeeding/ chestfeeding.

Finding Professional Help

In the community (for in-person support):

The 211 Greater Montréal helpline: dial 2-1-1 → 211 Greater Montréal
A CLSC (Local Community Service Centre)
A medical clinic

By phone (for free, 24/7 support):

Drugs: Help and Referral: 1-800-265-2626 → Drugs: Help and Referral
Parent Helpline (Tel-Jeunes Parents): 1-800-361-5085 → Parent Helpline
Info-Santé: dial 8-1-1

Online:

Society of Obstetricians and Gynaecologists of Canada (SOGC)
SOGC video: It’s more than just a weed
CHU Sainte-Justine: Cannabis, grossesse et allaitement

References

Reck, A. Matthew, et al. “Risks of Cannabinoid Exposure on Birth Outcomes: A Systematic Review.” Cannabis and Cannabinoid Research (2025).
Robinson, Tessa, et al. “Risk thresholds for the frequency of cannabis use during pregnancy and adverse neonatal outcomes: protocol for a systematic review and dose–response meta-analysis.” Systematic Reviews 13.1 (2024): 307.
Reyentanz, Emely, et al. “Systematic review: the impact of maternal pre-and postnatal cannabis use on the behavioral and emotional regulation in early childhood.” European Child & Adolescent Psychiatry 34.2 (2025): 423-463.
Sorkhou, Maryam, et al. “Birth, cognitive and behavioral effects of intrauterine cannabis exposure in infants and children: a systematic review and meta‐analysis.” Addiction 119.3 (2024): 411-437.
Sujan, Ayesha C., et al. “A systematic review of in utero cannabis exposure and risk for structural birth defects.” Frontiers in Pediatrics 11 (2023): 1149401.
Hayer, Sarena, et al. “Cannabis and pregnancy: a review.” Obstetrical & gynecological survey 78.7 (2023): 411-428.
Lo, Jamie O., et al. “Cannabis use in pregnancy and neonatal outcomes: a systematic review and meta-analysis.” Cannabis and Cannabinoid Research 9.2 (2024): 470-485.
Thompson, Mary, et al. “Prenatal cannabis use and its impact on offspring neuro-behavioural outcomes: A systematic review.” Paediatrics & Child Health 28.1 (2023): 8-16.

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