Project 465631

Cannabis became legal in Canada in October 2018. It is often marketed to pregnant women as a therapy for anxiety and nausea, among other symptoms, although its use has not been proven to be safe or effective during pregnancy. Research-guided information for parents and families remains scarce. Babies are exposed to substances their mothers use before birth. Cannabis can be transmitted via breast milk. Young children also breathe more quickly than adults and explore with their hands and mouths. Their small bodies get higher doses than adults. Babies and toddlers are growing and developing so have a higher risk of permanent health changes. For cannabis, long-term outcomes for babies and toddlers are not known. This project will build upon an existing study of 400 mother-infant pairs, 200 of which reported cannabis product use during pregnancy and 200 who did not. An existing CIHR-funded project follows mothers and babies for their mental and physical health, sleep, household air quality and child development to 18 months. This project proposes to extend the follow-up of those mother-child pairs until the children are 3 years old. We will examine the association between cannabis use and exposure and child development including IQ, functional skills, and behaviour at age 3. We will also collect information on mother and child sleep, air quality, and physical and maternal mental health to explore their impact on child development in the context of cannabis exposure. Mothers are unique because they need to care for their own health while minimizing risks to their children. Medical and recreational cannabis use presents both potential risks and benefits to mothers of young children. This study will provide valuable information to help families make informed choices about cannabis and set the stage for further research on the long-term effects of cannabis exposure on children.