Bookmark this page
Get the facts on marijuana and pregnancy
  • There is no known safe amount of cannabis (marijuana) use before pregnancy, during pregnancy or when breastfeedingMarijuana leaf
  • Marijuana (also known as pot, hash, Mary Jane, and weed) comes from the cannabis plant. The active ingredient in marijuana and other products from the cannabis plant, such as hashish and hash oil, is a substance known as tetrahydrocannabinol (THC). THC is the chemical that makes people feel high. 
  • If you have questions or want to quit using marijuana, see the links below for more information and where to go for help

Marijuana use before pregnancy

  • Couple sitting on fenceMarijuana use may affect the ability to become pregnant.
    • In females, marijuana use can cause changes to the menstrual cycle.
    • In males, marijuana use can lower sperm count and quality.
  • Marijuana smoke contains many of the same poisons and cancer-causing chemicals as tobacco smoke, which can cause damage to the lungs.
  • Long-term heavy marijuana use can make it hard for an individual to pay attention, learn and remember things.

Marijuana use during pregnancy

  • Pregnant womanIt is safest not to use marijuana during pregnancy.
  • Smoking marijuana can interfere with the supply of oxygen and nutrients to the baby.
  • THC, which is the active ingredient in marijuana, passes from mother to baby through the placenta.
  • Babies born to women who often used marijuana during pregnancy may:
    • be born too soon and be smaller than average,
    • have health problems,
    • show signs of withdrawal.
  • Exposure to marijuana during pregnancy may not be noticed until the child is in school. It may affect their:
    • memory and learning skills,
    • problem-solving skills,
    • emotional and behavioural controls, and
    • ability to focus and pay attention.
  • Any form of cannabis (marijuana) is not a safe treatment for nausea and vomiting during pregnancy. Talk to your health care provider about safer choices that do not risk harming your baby.

Marijuana use while breastfeeding

  • Mom breastfeedingBreastfeeding is the healthiest choice for your baby.
  • Mothers should not use marijuana while breastfeeding.
  • THC passes into breastmilk and then into a baby’s fat cells and brain.
  • THC can be stored for weeks in an adult’s or baby’s tissue.
  • Some research has found that infants exposed to THC through breastmilk had slower motor development but more studies are needed.

Where can I get more information?

Where can I get help?

It is never too late to reduce or stop using drugs. It can be very difficult to admit to drug use and ask for help. Finding support from someone you can trust is key to getting help. Your partner, family members, or friends may be a great source of support. Speak with your health care provider about services to help you quit safely.

  • Talk to your health care provider
  • Service guide for pregnant women and parents of young children PDF
  • Motherisk - to get information on substance use in pregnancy 1-877- 439-2744
  • Pinewood - for pregnant women or mothers of children (0-3 years) who are worried about their alcohol or drug use 1-800-825-6325
  • Durham Health Connection Line - to speak with a public health nurse 1-800-841-2729
  • Drug & Alcohol helpline - free health services and information 1-800-565-8603
  • Ontario Poison Centre - if your child has consumed an edible product 1-800-268-9017