Cannabis affects everyone across the lifespan

Cannabis: Preconception, pregnancy, and breast/chestfeeding

I am thinking of becoming pregnant, should I avoid cannabis?

If you are thinking about becoming pregnant or planning a pregnancy, you should be aware of the effects cannabis can have on your body. Being aware about the risks of cannabis can help you to make informed decisions when making choices about your health and your fertility.

Cannabis can cause changes to your menstrual cycle and in some cases affect your hormone levels making it difficult to conceive^1,2.
Cannabis can impact sperm function and sperm count^1,2.

People who use cannabis and are planning on becoming pregnant should speak to their health care provider about the risks of cannabis use before becoming pregnant. If you are already pregnant, talk to your health care provider.

For more information, read Best Start’s Risks of Cannabis on Fertility, Pregnancy, Breastfeeding, and Parenting (PDF).

If I am pregnant and smoke cannabis, can it hurt my baby?

Pregnant people should not use cannabis in any form during pregnancy. When cannabis is used during pregnancy, chemicals, such as THC, are carried through the bloodstream to the fetus. Smoking cannabis while pregnant also reduces the oxygen supply to the fetus. Using cannabis while pregnant can lead to^3,4:

low birth weight
preterm labour or premature birth

Cannabis use during pregnancy can also cause long-term developmental effects as the baby grows such as difficulties with the heart and lungs, behaviour, and learning problems. The safest choice is to not use cannabis while pregnant^3,4.

For additional information:

What you need to know: Cannabis, Pregnancy and Breastfeeding (PDF) from the Society of Obstetricians and Gynecologists of Canada (SOGC).
Best Start’s Risks of Cannabis on Fertility, Pregnancy, Breastfeeding, and Parenting (PDF).

Can I use cannabis during pregnancy to help with morning sickness?

Pregnant people should not use cannabis in any form (edibles, smoking, vaping) during pregnancy. Speak with your health care provider about alternative safe treatment options if you are experiencing morning sickness symptoms such as nausea and vomiting.

Can I use cannabis if I breast/chestfeed?

Breast/chestfeeding parents should avoid using cannabis for the duration of the time they are breast/chestfeeding their child. Using cannabis while breast/chestfeeding may have negative impacts on your child because THC and CBD pass through breast/human milk^3,5.

There is limited clinical evidence on the long-term effects of cannabis exposure through breast/human milk, however, current evidence suggests the following are potential risks to your child if you use cannabis while breast/chestfeeding^3,5,6:

increased sedation (grogginess, delayed response) of the baby
poor suckling
reduced muscle tone
decreased or slowed motor development

Other potential long-term risks include difficulties with behaviour and learning (also referred to as cognitive development)^3,5. Additionally, if a parent is impaired by cannabis, their ability to recognize a baby’s hunger cues and to make decisions about an infant’s needs and safety can be affected^2,5.

It is important to note that cannabinoids like THC do not filter through the body the same way as alcohol because THC is stored in body fat. Using the “pump and dump” method or waiting for your body to fully metabolize or filter out the cannabis will not remove it from your milk supply in the matter of a few hours. The clinical evidence on the amount of time it takes for THC to leave the milk supply varies but has been reported to take from 17 days to up to 6 months^3,5.

While the safest approach is not using cannabis while breast/chestfeeding, this may not be possible for everyone. If this is the case for you or you have questions or concerns, it is recommended you consult with a trusted health care provider. You can also read Taking Care: A short guide to breastfeeding and substance use (PDF) which contains information on substance use, harm reduction and breast/chestfeeding from the Centre of Excellence for Women’s Health.

Wellington-Dufferin-Guelph Public Health. (n.d.). Cannabis before, during and after pregnancy. https://wdgpublichealth.ca/sites/default/files/file-attachments/basic-page/cannabis_and_pregnancy_fact_sheet_2024.pdf
Best Start by Health Nexus. (2019). Risks of cannabis on fertility, pregnancy, breastfeeding and parenting. https://resources.beststart.org/product/a30e-risks-of-cannabis-booklet/
Canadian Centre on Substance Use and Addiction (CCSA). (2022). Clearing the smoke on cannabis: Cannabis use during pregnancy and breastfeeding—An update. https://www.ccsa.ca/clearing-smoke-cannabis-cannabis-use-during-pregnancy-and-breastfeeding
The Society of Obstetricians and Gynaecologists of Canada (SOGC). (n.d.). Cannabis. Pregnancy info. https://www.pregnancyinfo.ca/your-pregnancy/healthy-pregnancy/substance-use-in-pregnancy/cannabis/
Nathoo, T., Stinson, J., Poole, N., & Wolfson, L. (2021). Breastfeeding and cannabis: A harm reduction resource for health care and social service providers. Centre of Excellence for Women’s Health. https://cewh.ca/wp-content/uploads/2022/01/Breastfeeding-and-Cannabis_Dec-6-2021-FINAL-WEB.pdf
(n.d.). What you need to know: Cannabis, pregnancy and breastfeeding. https://www.pregnancyinfo.ca/wp-content/uploads/2019/12/SOGC_13333_cannabis_posters_2_infographic_EN.pdf

This item was last modified on September 10, 2024