During pregnancy, does cannabis consumption carry a risk for the baby?

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Yes. The consumption of cannabis (marijuana) during pregnancy has risks for the foetus, even in small quantities.

Cannabis use should be avoided before, during and after pregnancy. First of all, the active ingredient in cannabis, THC (delta-9-tetrahydrocannabinol), is transmitted to the foetus through the placenta. This substance can remain in the body of the foetus for up to a month and a half after consumption, and can have adverse developmental effects. Marijuana today is stronger than before: it contains 300% to 400% more THC and very often other harmful products that vary according to the producer and seller.

On the other hand, cannabis has the same vasoconstrictive effects as cigarette, meaning that it reduces the size of blood vessels. Therefore, when the mother smokes marijuana, the foetus gets fewer nutrients and oxygen, which hinders its development.

Several risks (non-exhaustive) for the baby are associated with cannabis use during pregnancy:

  • low birth weight;
  • growth delay;
  • small size;
  • small head circumference;
  • learning disabilities, attention deficit, behaviour problems, memory loss and sleep disorders;
  • hyperactivity, impulsivity;
  • delinquency;
  • executive function disorders (planning, organization);
  • psychiatric disorders (anxiety, depression).

The effects on growth and risk of prematurity appear to be higher with more frequent exposure or long-term exposure compared to infrequent or short exposure. For example, a higher growth delay was observed when the mother used cannabis throughout her pregnancy. A slight decrease in the duration of pregnancy (premature birth) was also observed with a consumption of 5 or more times a week. The fact remains that any consumption, frequent or occasional, poses a foetal health risk. Even second-hand smoke is not without risk. For more information, see the following article (coming soon).

Abstinence is called for during pregnancy. If abstinence is not possible, a reduction in consumption should be considered with professional support to help the mother in this process.

It is important to always consult a doctor in case of addiction (drugs, alcohol, tobacco).


CHUM ST-LUC, department of addiction MeDECINE

Phone : 514 890-8321

Website : http://www.chumontreal.qc.ca/patients-et-soins/departements-et-services/toxicomanie


Phone : 514 385-1232

Website : http://dependancemontreal.ca/contact

LE ROND-POINT intervention center

Phone, no fees : 1-877-962-7333

Website : http://www.lerondpoint.org/

DRugs : help and referral

Phone : 514-527-2626 or 1-800-265-2626

(24/7 service, no fees)

Website : www.drogue-aidereference.qc.ca


Phone : 1-877-327-4636 (9 to 5, Monday to Friday)

Website : www.motherisk.org


Montraal : 514-288-555
Other regions : 1-800-361-5085


Website : http://www.toxquebec.com/ressources/centres-de-traitement.html

Other resources : http://www.toxquebec.com/ressources/prevention.html


Brandon A. R. (2014). Psychosocial Interventions for Substance Use during pregnancy. Journal of Perinatal Neonatal Nursing, 28(3), 169-177.

Centre canadien de lutte contre les toxicomanies. (2013). Consommation de drogues licites et illicites pendant la grossesse : Répercussions sur la santé maternelle, néonatale et infantile.


Centre canadien de lutte contre les toxicomanies. (2015). Dissiper la fumée entourant le cannabis : Effets du cannabis pendant la grossesse.


Destinationsanté.com. (2014). Enceinte… et accro au cannabis.


Hill. M., et Reed K. (2013). Pregnancy, Breast-feeding, and Marijuana : A Review Aticle. Obstetrical and Gynecology Survey, 68(10), 710-718

Holbrook B.D. et Rayburn W. F. (2014). Teratogenic Risks from Exposure to Illicit Drugs. Obstetrics and Gynecology Clinics of North America, 41(2), 229-239.

James A. et Windrim R. (2014). Les choses à éviter pendant la grossesse : Les tératogènes.


Lamy S., Laqueille X. et Thibaut F. (2014). Conséquences potentielles de la consommation de tabac, de cannabis et de cocaïne par la femme enceinte sur la grossesse, le nouveau-né et l’enfant: revue de littérature. L’encéphale, 41(1), S13-S20.

Centre canadien de lutte contre les toxicomanies. (2015). Dissiper la fumée entourant le cannabis (ISBN 978-1-77178-225-8).


Stop-cannabis.ch. (2015). Cannabis et grossesse : quel risque pour l'enfant ?



Centre canadien de lutte contre les toxicomanies. Nos ressources.

Gouvernement du Canada. (2015). Au sujet de la marijuana.

Naître et grandir. (2013). Cannabis et autres drogues durant la grossesse.

Santé et services sociaux Québec. (2015). Enceinte? Alcool et drogues, ce qu’il faut savoir.

Toxquebec.com. Cannabis.


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