Questions about Cannabis in Pregnancy

*Please note that the terms “marijuana” and “cannabis” are used interchangeably in this post.

In Canada with the legalization of recreational marijuana many people are using marijuana and are wondering:

Is it safe to use marijuana or cannabis products in pregnancy or while breastfeeding?

The short answer: Given the information we have at this time, the only safe amount of cannabis to use is ZERO.  There is no known safe level of marijuana use for pregnant and breastfeeding women.

The long answer: A lot of research has been done on the effects of cannabis on pregnant women, their fetuses, the fertility of men and women, and breastfeeding infants. It is difficult to interpret the studies on effects of cannabis due to many factors:  all the studies rely on people self-reporting their use (which is usually more than reported), the difficulty in understanding dosages, strengths, and types of cannabis products, and the influence of other substances people might be using at the same time  (such as cigarettes, alcohol, and other drugs).  However, many studies are showing similar harms from cannabis use and they are worrisome.  Marijuana use in pregnancy has been associated with low newborn birth weight which is associated with many other health problems. The most worrying effects that have been shown in research are on children’s thinking ability (decreased memory and learning) and behaviour (poor attention and hyperactivity), which may be lifelong.  As well, exposed children are more likely to use marijuana and other drugs as a teen.  Cannabis chemicals are passed into breast milk and may have ongoing effects on brain development and functioning. Second-hand marijuana smoke can cause some of the same health problems for children as second-hand tobacco smoke. Marijuana use has been associated with infertility in both men and women. Finally, as a parent, using marijuana may affect your ability to safely take care of your baby.

How does cannabis affect the brain?  We know that the human brain makes many natural chemicals like cannabinol and is very sensitive to them. These chemicals are important in regulating brain growth and development in the fetus, and brain functioning. Cannabis chemicals go into the bloodstream of the fetus and into breast milk.  They may interfere with the normal functioning and development of the nervous system. Marijuana contains over 400 chemicals and we don’t know a lot about their effects.

What can I do?

The safest thing is to avoid cannabis products altogether while trying to get pregnant, while pregnant, breastfeeding, and caring for young children. If you use marijuana for nausea and vomiting, there are much safer alternatives. If you are a regular user and cannot stop, reduce as much as possible, use low THC, avoid vaping (which puts other dangerous chemicals into your lungs and blood), and speak to your family doctor or maternity health care provider for help with physical or mental health issues and assistance in how to reduce or stop.  Being open and honest will help you and your baby.

How can I find reliable information about marijuana and cannabis in pregnancy and breastfeeding?

Safe treatment of nausea and vomiting in pregnancy:

Here-to-help: Questions and help with alcohol and drug use in Vancouver:

Pregnancy Vancouver is a project of the Vancouver Division of Family Practice (VDoFP). The VDoFP is creating a network of Family Doctors to enhance and facilitate knowledge exchange about prenatal and postpartum care, connect Family Doctors, and improve the maternity care referral process.