Cannabis use in pregnancy and breastfeeding has become more common in Canada despite research suggesting a negative impact on fetal health outcomes. Still, very little is known about why pregnant and lactating people use cannabis, how they decide to use it, and how prenatal and postpartum health care providers can better support and advise patients around this topic.
The cannabis use during pregnancy and lactation project will be done in three phases and will look at:
- Current research exploring perspectives of pregnant and lactating people and prenatal care providers on cannabis use during pregnancy and lactation.
- Pregnant and lactating people’s experiences using, discussing and making choices to use or stop using cannabis during pregnancy and lactation.
- Primary prenatal or postpartum care providers’ experiences with barriers and facilitators to counselling about cannabis use during pregnancy and lactation.
Funding: Canadian Institutes of Health Research, McMaster University Department of Family Medicine
Frequently Asked Questions (FAQs)
Pregnancy:
- Are there risks to the baby if I use cannabis during pregnancy?
There are not a lot of high quality scientific studies to tell us exactly what will happen when cannabis is consumed during human pregnancy. The available evidence suggests cannabis use during pregnancy may cause complications such as low birth weight, babies being born too early (pre-term birth) and have some impact on development during childhood (1-3). Kids who were exposed to cannabis before birth had issues with things like paying attention, being hyperactive, and acting impulsively during their early childhood (4, 5).
While there is not a lot of good quality clinical evidence in humans, there is a lot of research about how some parts of cannabis affect human cells or pregnancy in mice or other animals. Typically these studies haven’t researched the whole cannabis flower, but instead study different components of cannabis. These studies suggest that cannabis can impact fetal growth or cause low birth weight (6, 7). They also suggest that cannabis can impair the development and functioning of the placenta, which is a very important organ for fetal development and growth (6, 8, 9).
If you can stop using cannabis when pregnant, that is the safest thing for your baby.
- Are there risks to me if I use cannabis while pregnant?
Maternal risks of using cannabis during pregnancy are not well-studied. Mostly, what we know is that the risks of consuming cannabis are the same whether you are pregnant or not. These risks include changes in thinking and memory, addiction, problems with your breathing and heart, as well as mental health issues like schizophrenia and mood disorders (10-14). There is one study showing an additional risk of consuming cannabis while you are pregnant – you are more likely to experience anemia, which means low levels of iron in your blood (1). There is some evidence that if you are anemic when pregnant, the baby’s brain development is affected. This may increase the risk that child will have autism, attention deficit/hyperactivity disorder (ADHD) or intellectual disability.(15, 16)
- Is it okay just to consume CBD products without THC during pregnancy?
The short answer is no, CBD is likely to be a part of cannabis which causes health problems, even though it doesn’t make you feel high.
Cannabis is comprised of many different chemicals called cannabinoids, but two commonly known ones are THC and CBD. THC is the part of cannabis that can make you feel high, while CBD doesn’t have this effect and is considered “non-psychoactive”- that means that your mind and consciousness feel the same as usual after you consume it.
There have been no clinical studies in humans looking at the safety of CBD during pregnancy. Limited research suggests that CBD may potentially pass through the placental barrier if used during pregnancy. (17) Research on placental cells in humans and on mice shows us that CBD can have negative effects on fetal and placental development (18, 19). This helps us know that even though it doesn’t make you feel high, CBD is still disrupting normal pregnancy development.
- Cannabis is natural, does this mean it is safe to use?
Although cannabis is derived from a natural plant, there is not enough evidence to suggest that it is safe to use during pregnancy, and actually quite a bit of evidence to suggest it is not safe (see question 1 and 2). Opium and arsenic are also plant-based substances, and they are not safe to consume in pregnancy.
While pharmaceutical drugs may feel more risky to some people because they are made in laboratories, many drugs prescribed during pregnancy are known to be safe. They are tested through rigorous studies that carefully measure what happens to people who are using these substances. This level of evidence doesn’t exist about cannabis, and so it is not possible to make clear conclusions about the safety of cannabis in the way that it is for other drugs frequently prescribed in pregnancy, like pyridoxine or doxylamine drugs (e.g. Diclectin), which we know to be safe from decades of well-designed scientific studies. (20, 21)
- Would it be safer if I changed the amount, form, or strain of cannabis that I am using?
There is currently no evidence to suggest the safety of changing the amount, form, or strain of cannabis for use during pregnancy or breastfeeding. Hopefully in the future, evidence to support these kinds of harm reduction strategies will be available, but right now it is just not possible to say what is safer or riskier.
Because we know that cannabis affects developing brains and other parts of the body, it is safest to minimize your exposure to cannabis during pregnancy and lactation.
- I’ve decided I’m going to use cannabis, should I get it from a regulated store, or should I get it from my regular (unregulated) source?
Public Safety Canada recommends that if you are using cannabis seek it from an authorized retailer/dispensary to avoid contamination of pesticides, lead, or other substances. (22) Some public health units in Canada have released warnings that they have found cannabis laced with fentanyl, a very strong opioid which can cause a lot of harm and even death in a very small amount (23). These accounts have not been verified, but getting your cannabis from a regulated store/dispensary could reduce the chance that it might be contaminated with any substance.
- How do I talk to my provider about cannabis use during pregnancy?
Health care providers are used to these kinds of questions and their role is to help you have a healthy pregnancy. You might be afraid that they will judge you, and these are valid feelings, but many healthcare providers are used to these kinds of questions and will be glad that you are seeking information to make a decision for the health of your pregnancy.
If you are nervous about bringing this question up with your health care provider, you could use a hypothetical example. For instance, you could say, “I’m thinking about using cannabis during pregnancy to help with my feelings of nausea and vomiting (or whatever reason you want to use it). What do you know about cannabis use during pregnancy that could help me make this decision?” This type of question will help them understand why you are interested in cannabis use, and they can explore that topic with you, including the safety of cannabis for that purpose and other alternatives known to be safe.
Alternatively, you can ask about the potential consequences of using cannabis during pregnancy in a hypothetical scenario to gauge your healthcare provider’s response. You could use wording like “I’ve heard that some people use cannabis when pregnant to help with their anxiety. What would you recommend for someone who is feeling anxious while pregnant?”
- Will my healthcare provider report me to children’s aid society/child protective services if I tell them I am consuming cannabis while pregnant?
We cannot say for sure what your healthcare provider will do, but research and review of guidelines and regulations suggest that clinicians will not call children’s aid society for cannabis use during pregnancy, if that is the only concern that they have.
In a recent study where healthcare providers were interviewed about calling Children’s Aid Society (CAS) or child protective services if a pregnant patient was consuming cannabis, the health care providers described that they would only call CAS if the patient’s cannabis use posed a direct risk to the safety of the child. For example, if the patient was neglecting her children in order to buy and consume cannabis. One doctor in the study compared smoking cannabis during pregnancy to smoking cigarettes. The evidence suggests that both substances have negative health effects, but he wouldn’t call CAS for either one.
There are no Canadian guidelines which suggest that clinicians should report people who use cannabis while pregnant or breastfeeding.
Breastfeeding:
- What are the risks of using cannabis during breastfeeding?
There have been very few studies that have looked at the risks of cannabis exposure through breastfeeding- even fewer than in pregnancy! We do know that cannabis (THC and CBD) passes through the breastmilk to the baby, and that cannabis can stay active in the breastmilk from 6 days to 6 weeks (24, 25). Limited evidence has conflicting results on the impact of cannabis on infant motor development, with some showing that babies exposed to cannabis through breastmilk have slower development of physical motor skills and another study showing no effect (26, 27). Other research shows that cannabis could potentially alter the content of breastmilk by decreasing immunoglobulins and increasing lactose, which means that the baby gets less of the good stuff from the breastmilk. (28)
- If I don’t breastfeed the baby for a while after I take cannabis, will it impact the baby?
Cannabis reaches its highest level of effect for the user within the first hour after consuming. However, it takes roughly 25 to 36 hours for half of its activity and potency to diminish, meaning that half of the cannabis will remain in your body during this time. (29) As cannabis will still remain in your body, it may impact the baby if you breastfeed even a few days after consuming cannabis. That said, the concentration of THC in breastmilk does diminish as time passes, so if you are going to breastfeed after consuming cannabis, the longer you can wait the less will be transferred to your baby.
- Should I stop breastfeeding if I want to start consuming cannabis again?
This is a question only you can answer. There are many benefits of breastfeeding for both you and your infant, particularly during the first 6 months of life. It improves the baby’s brain development, reduces risks of obesity for both mom and baby, and also reduces risk of diabetes, high blood pressure, and even some kinds of cancer (30). There is also evidence that breastfeeding can help protect against stress and postpartum depression (31). For babies, it can enhance lifetime immunity (32-34).
As described above, while we know that cannabis is transferred through breastmilk for as long as 6 weeks after the mother consumes cannabis, there is not a lot of clear evidence on what that means for the baby. It is reasonable to conclude that there are negative effects on the baby’s developing brain, but there are so many positive effects of breastfeeding that it is difficult to decide to stop breastfeeding in order to resume cannabis consumption. Some have advised that while it is best to not consume cannabis while breastfeeding, the next best thing to do is reduce your cannabis use while continuing breastfeeding and wait as long as possible after consuming cannabis to feed (27).
- Will my healthcare provider report me to children’s aid society/child protective services if I tell them I am consuming cannabis while breastfeeding?
We cannot say for sure what your healthcare provider will do, but research and review of guidelines and regulations suggest that clinicians will not call children’s aid society for cannabis use while breastfeeding, if that is the only concern that they have.
In a recent study where healthcare providers were interviewed about calling Children’s Aid Society (CAS) or child protective services if a pregnant patient was consuming cannabis, the health care providers described that they would only call CAS if the patient’s cannabis use posed a direct risk to the safety of the child. For example, if children or infants experienced neglect as a result of their parent consuming cannabis.
There are no Canadian guidelines which suggest that clinicians should report people who use cannabis while pregnant or breastfeeding.
Access references for this FAQ here: Vanstone – CanPreg- FAQ Patients -References
There is limited clinical evidence that discusses the outcomes of contemporary cannabis use during pregnancy and while breastfeeding.
In our recent study, pregnant and lactating patients who considered using cannabis sought information from many sources. However, they were relatively unlikely to talk with their clinician about their cannabis use because they are worried about stigma, and/or increasing the likelihood of being reported to child protective services.
Here are some of the most frequent questions we heard from patients about cannabis use during pregnancy or lactation, with brief responses. You may also wish to refer patients to our patient-facing knowledge resource, Cannabis during pregnancy or breastfeeding: Frequently Asked Questions, in the tab above.
| Questions your patients may have | Potential responses |
| Are there risks to the baby if I use cannabis during pregnancy? | There is a lack of evidence and information on what the exact the risks are. With what exists, we know that consuming cannabis during pregnancy might lead to complications such as low birth weight, pre-term birth, placental function, and cognitive development in early childhood. (1-8) |
| Are there risks to me if I use cannabis while pregnant? | Mostly, what we know about risks to you are the same in and outside of pregnancy. Some maternal risks may include changes in memory and thinking, problems with breathing and heart, and mental health issues such as schizophrenia and mood disorders. (9-13) |
| Is consuming CBD without THC during pregnancy a better option? | As cannabis is comprised of many chemicals, there have been no clinical studies in humans that look at the safety of CBD vs. THC. We do know that CBD can pass through the placental barrier, (14) and research on mice has shown CBD to result in negative prenatal development. (15, 16) This helps us know that even if CBD doesn’t make you feel high, it can still disrupt normal pregnancy development. |
| Cannabis is natural, does that mean it is safe to use? | Although derived from a plant, the evidence does not suggest that cannabis is safe to use during pregnant. Many participants raised concerns about pharmaceutical drugs feeling less safe, but providing reassurance that they are rigorously tested, and carefully created may ease those worries. |
| Does the amount, form, or strain change the safety of using cannabis? | There is no evidence to suggest that changing those attributes will be safe during pregnancy and breastfeeding. Hopefully in the future there will be evidence to support harm reduction strategies, but right now it is not possible to say what is safer or riskier. |
| Your pregnant patient has decided to use cannabis. Is it recommended to get it from a regulated dispensary or their regular source? | Public Safety Canada guidelines recommend that any person consuming cannabis obtain that product from authorized retailers in order to avoid the risk of contamination (e.g., pesticides, lead, or other substances). (17) |
| Your patient wants to know how to talk to their providers about cannabis use and pregnancy. | We recommend that if patients are nervous to disclose or talk about it that they could present it as a hypothetical scenario to gauge a response. Remaining non-judgemental, remaining neutral, sharing information/resources, and focusing on the outcome of a healthy pregnancy is important to patients.
As a clinician, you could raise this question with your patients to remove some of that stigma, perhaps using language like “many people wonder if it is ok to keep using cannabis now that they are pregnant. Some people find it very helpful to manage certain conditions or symptoms. Is this something you would like to discuss?” |
| Your patients are concerned that they will be reported to child protective services. | Our study found that clinicians would likely not report their patient unless there was a direct safety risk to the child (e.g., neglect, driving under the influence, etc.)
Making clear to your patients what your reporting obligations are may help them feel more comfortable discussing this topic, or asking questions about their own circumstances or concerns. You could use language like: “Some patients are thinking about consuming cannabis while they are pregnant, but they don’t want to talk about it with their doctor in case that person decides to report them to Children’s Aid Society. I want you to know that I am open to talking about this with you, and that simply knowing you are thinking about using cannabis would not make me consider calling CAS unless there were other factors at play, such as the child being neglected as a result of their parent consuming cannabis” |
| What are the risks of using cannabis during breastfeeding? | As there is a lack of scientific evidence, it is important to share the information that is available. Cannabis (CBD and THC) passes through breastmilk and can be active in the system for 6 days – 6 weeks. (18, 19) However, there is very limited evidence about the clinical effects of this transfer. There are some older studies that show cannabis transferred through breastmilk may impact infant motor development, while another study shows no effect.(20, 21) Other research suggests that cannabis use could decrease immunoglobins passed through breastmilk. (22) |
| If patients wait after taking cannabis to breastfeed, what are the potential impacts? | Within the first hour after use, cannabis potency is at its highest. However, it remains in the body for approximately 25 – 36 hours. (23) The concentration of THC diminishes over time, so feeding with formula or pre-pumped breastmilk after consuming cannabis may help diminish the transfer of cannabis to baby. |
| If your patient wants to use cannabis, should they stop breastfeeding? | During the first 6 months of life, breastfeeding has shown to be beneficial for brain development, reduce risk of diabetes, high blood pressure, and some types of cancer. (30) It can also enhance immunity. (24-26) Lastly, it may protect against stress and postpartum depression. (27) As described above, cannabis can be transferred to baby through breastmilk, and it is reasonable to conclude that there are negative effects of this transfer on baby’s developing brain. However, there are so many positive effects of breastfeeding, this can be a difficult decision. Some have advised that while it is best to not consume cannabis while lactating, the next best thing to do is reduce your cannabis use while continuing to breastfeed and waiting as long as possible after consuming cannabis to feed the baby. (21) |
Additionally, below are some resources that can be used to guide your harm reduction information and may be used to guide your patients.
- The American College of Obstetricians and Gynecologists: Marijuana Use During Pregnancy and Lactation. https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/10/marijuana-use-during-pregnancy-and-lactation
- The society of Obstetricians and Gynaecologists of Canada: Are you pregnant, considering pregnancy, or breastfeeding? https://www.pregnancyinfo.ca/learn-more/
- The society of Obstetricians and Gynaecologists of Canada: Your pregnancy – Cannabis. https://www.pregnancyinfo.ca/your-pregnancy/healthy-pregnancy/substance-use-in-pregnancy/cannabis/
- American Academy of Pediatrics: Marijuana Use by Breastfeeding Mothers and Cannabinoid Concentrations in Breast Milk. Bertrand et al., 2018.pdf
- Government of Canada: Thinking about cannabis while parenting? https://www.canada.ca/en/health-canada/services/drugs-medication/cannabis/health-effects/parents.html
- Centre for Disease Control and Prevention: Pregnancy – What you need to know about marijuana use and pregnancy. CDC – Marijuana and Public Health.pdf
Access references for this FAQ here: CanPreg – FAQ – Clinicians – V2.0 – References
Phase 1
Systematic review & integrative mixed-methods research synthesis
In this phase, we conducted two systematic reviews. The first describes the perspectives, experiences and information needs of pregnant and lactating people in how they make decisions about using cannabis during pregnancy and lactation. The second describes the perspectives, attitudes and beliefs of prenatal or postpartum health care providers on cannabis use during pregnancy or lactation and their experiences providing counselling to patients around this topic.
Phase 1: Publications
Clinician responses to cannabis use during pregnancy and lactation: A systematic review and integrative mixed-methods research synthesis Learn More
Panday, J., Taneja, S., Popoola, A., Pack, R., Greyson, D., McDonald, S. D., Black, M., Darling, E., & Vanstone, M. (2022). Family Practice, 39(3), 504-514.
This article received the 2022 Family Practice/North American Primary Care Research Group Best Paper award.
Pregnant people's perspectives on cannabis use during pregnancy: A systematic review and integrative mixed-methods research synthesis Learn More
Vanstone, M., Panday, J., Popoola, A., Taneja, S., Greyson, D., McDonald, S. D., Pack, R., Black, M., & Darling, E. (2022). Journal of Midwifery & Women’s Health, 67(3), 354-372.
Phase 1: Knowledge Translation Materials
Phase 2
Qualitative study – Pregnant and lactating people’s perceptions about cannabis during pregnancy & lactation
For this phase we explored how people make decisions about cannabis use during pregnancy and breastfeeding. This included their information needs, preferred sources of information, perceived risks, strategies to lower risks and desired clinical counselling approaches.
We recruited participants with the following characteristics:
- Pregnant or breastfeeding within the past year
- Used cannabis during pregnancy or lactation OR used cannabis at least once in the three months before their most recent pregnancy
- Able to participate in an interview in English and provide consent
We interviewed participants to better understand their experience navigating this decision-making process.
Phase 2: Publications
Making informed choices about cannabis use during pregnancy and lactation: A qualitative study of information use Learn More
Taneja, S., Panday, J., Popoola, A., Greyson, D., McDonald, S. D., Patel, T., & Vanstone, M. (2023). Birth, 50(3), 504-512.
Reasons for cannabis use during pregnancy and lactation: A qualitative study Learn More
Vanstone, M., Taneja, S., Popoola, A., Panday, J., Greyson, D., Lennox, R., & McDonald, S. D. (2021). CMAJ: Canadian Medical Association Journal, 193(50), E1906.
Pregnant and lactating people’s strategies to mitigate the risk of cannabis consumption Learn More
Popoola, A., Panday, J., Taneja, S., Greyson, D., McDonald, S. D., Patel, T., Darling, E., & Vanstone, M. (2023). Women’s Health.
Counseling about cannabis consumption during pregnancy and lactation: A qualitative study of patient and clinician perspectives Learn More
Cernat A, Carruthers A, Taneja S, Popoola A, Greyson D, Panday J, Darling E, Mcdonald SD, Black M, Murray, Davis B, Vanstone M. Birth. 2024;51(4):867–77.
Phase 2: Media Coverage
Phase 2: Knowledge Translation Materials
Phase 3
Qualitative study - Clinician - perceived barriers to counselling about cannabis during pregnancy & lactation
For this phase, we explored what prenatal and postpartum care providers think helps or hinders them in supporting informed decisions when counselling people about cannabis use during pregnancy and breastfeeding. We recruited participants with the following characteristics:
- Prenatal or postpartum care providers who work in Canada
- People who self-identify as providing care to patients who are pregnant and/or breastfeeding
We interviewed participants such as family physicians, midwives, and obstetricians.
Phase 3: Publications
Counseling about cannabis consumption during pregnancy and lactation: A qualitative study of patient and clinician perspectives Learn more
Cernat A, Carruthers A, Taneja S, Popoola A, Greyson D, Panday J, Darling E, Mcdonald SD, Black M, Murray, Davis B, Vanstone M. Birth. 2024;51(4):867–77.
