Cannabis and Pregnancy

Health advice

More and more pregnant women are questioning the use of cannabis during pregnancy, whether to relieve nausea, reduce stress or manage certain types of pain. However, although cannabis is perceived by some as a natural solution, its effects on fetal development remain a cause for concern. Whether smoked, vaped or ingested in edible form, its consumption is not without risk to the health of the unborn baby. In this article, we take a look at the potential impact of cannabis during pregnancy, and the precautions you can take to protect your well-being and that of your unborn child.

Cannabis is a topic making headlines with its recent legalisation in Canada. The product is still controversial, as everyone has a different opinion about it. Of course, I respect everyone’s opinion! However, just because we hear about cannabis frequently, and that the use of cannabis seems to be more socially acceptable, that you should take its use lightly in all situations. Unfortunately, new cannabis users include pregnant women, and this is concerning. When asked, “Do you use drugs?” some young women will answer no. However, when they’re asked, “Do you use cannabis or THC?” they answer, “Of course! All the time!” as if it wasn’t important.

We clearly know that marijuana, cannabis, pot, joints, grass or whatever you want to call it’s the most consumed harmful substance during pregnancy, and its use can impact the growing fetus.

Cannabis Addiction

Contrary to popular belief, some people can become addicted to cannabis at any age.

Frequent and prolonged use of cannabis by anyone can lead to physical addictions, abuse, and lead to serious health risks, including for pregnant women who are carrying a developing baby.

Studies have shown that THC found in cannabis increases dopamine concentrations. This is a chemical substance that produces the pleasure feeling in the brain. People increase their consumption to get this feeling.

Cannabis use by pregnant women

Cannabis use among pregnant women is more common than we think. Cannabis is the second most common psychoactive substance dependence during pregnancy, after alcohol (INSPQ 2023). Even if we have an idea of the growing statistics on cannabis use during pregnancy, many pregnant women won’t admit their use to their caregiver. They hide the fact that they use cannabis occasionally or regularly, to avoid judgment or criticism that would further increase their sense of guilt.

Given that the first trimester of pregnancy is a period of great growth and development for the fetus, it’s essential to be transparent with your health-care professional to get the support and help you need to stop using cannabis as soon as possible and minimize its impact during pregnancy.

Potential effects of cannabis during pregnancy

Cannabis use can have an impact on pregnancy outcome and fetal development. We don’t know exactly what these are, considering the product used, the quantity consumed and the trimester of exposure for the baby.

During pregnancy, at least 10% of the THC consumed can pass from the mother’s placenta to her fetus. The higher the concentration, the greater the effects. It is also this ingredient that will remain present in the body for several days, even weeks, as it is stored in fat reserves, even if the mother-to-be has stopped using it. Despite a very low dose, cannabis components can remain in the foetus’ body for up to 1.5 months. The concentration of THC can also be found in breast milk via fat cells.

Potential impacts on the pregnancy:

  • Miscarriage risk (spontaneous abortion)
  • Premature labour risk (if consumed heavily and regularly)
  • Risk of preeclampsia
  • Risk of placental abruption
  • Risk of hormone imbalance during pregnancy, childbirth and breastfeeding (including complications with milk production).
  • Cannabis, like nicotine, constricts blood vessels, which can limit the transmission of nutrients and oxygen to the growing baby. 

The Journal of Obstetrics and Gynaecology Canada (SOGC, 2022) specifies that there is very little scientific evidence that cannabis use during pregnancy helps relieve nausea and vomiting, as well as certain pre- or post-natal pains.

Possible effects on the fetus:

 If the pregnant woman uses both tobacco and cannabis, the impact on the baby is increased.

At birth:

  • Smaller head circumference (smaller cranial perimeter)
  • Growth delays
  • Low birth weight
  • Sleep disorders
  • Deprivation or withdrawal symptoms (trembling, irritability, slower reflexes, less reactive)
  • May have a cognitive impairment

Longer term (child or adolescent):

The brain develops until the age of 20 and can be influenced at any time. Children aren’t less intelligent, but effects may show up at different times over their lives, sometimes between 10 and 15 years:

  • A lowering:

        – Of memory capacity (memory problems)

        – Of concentration capacity (attention disorder)

        – Of reasoning and problem-solving skills

  • Hyperactivity
  • Learning and behavioural disorders (impulsivity)
  • Mental health problems, mood issues (anxiety, depression)
  • Increased risk of addiction problems in the future

Heavy cannabis use during pregnancy can cause the drug to invade and affect the normal brain development (cognitive and behavioral development) of the developing baby.

Breastfeeding and cannabis

Cannabis toxins are carried by the pregnant woman’s blood to the fetus, and are also found in breast milk, via fat cells, 8 times more than during pregnancy, as breast milk has a high fat content. Cannabis use can also have a negative impact on breast milk production by inhibiting prolactin secretion.

Any drug use, whether occasional or regular, low or high, carries risks. Cannabis use during pregnancy is a risk factor. Although the full extent of the phenomenon surrounding cannabis use during pregnancy and breastfeeding is not yet known, the fact remains that the known apparent dose-response relationship between prenatal cannabis exposure and persistent neurocognitive/neurobehavioral effects on the fetus or newborn is a strong argument for reducing or stopping cannabis use during pregnancy and breastfeeding

Caution! Some synthetic products on the market are designed to limit the effects of cannabis. These products are very dangerous and should never be used during pregnancy.

In case of need

Drugs : help and referral at 1 800 265-2626, available 24/7.

Marie Fortier
The Baby Expert

Updated article : March, 2025.

References:

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The mariefortier.com website and the comprehensive information it contains are intended as practical tools for expectant parents preparing for the arrival of their baby. These are not meant to replace the skills, knowledge, and experience of qualified health professionals who are familiar with the facts, circumstances, and symptoms specific to each individual. As such, Marie Fortier Inc. and its employees cannot be held responsible for any potential adverse effects or consequences resulting from the use of information provided on this website. It is the user’s responsibility to consult a physician or other qualified health professional for personal matters concerning them.