Grant: Op. Gr.:Cannabis Res. in Longit. studies-Neurosciences, Ment. health/Addiction

There is an immediate need for improved research of the risks of prenatal cannabis exposure to infant and child development and mental health to inform evidence-based, targeted education and intervention in Canada. Since legalization, cannabis use in pregnancy is on the rise. The effects of cannabis use in pregnancy on infant and child development remains unclear due to limitations in previous studies; prenatal cannabis use is difficult to measure accurately, because substance use is commonly concealed or underreported during pregnancy. Additionally, most studies were unable to untangle the potential effects of cannabis from those of alcohol and other substance use. We will conduct a study using accurate biological tests to detect cannabis in blood samples from early and late pregnancy in 1950 participants from a representative pregnancy cohort study, and examine how it is associated with measures of infant and child development and mental health up to age 13. We will also conduct brain MRI scans and detailed psychological assessments to measure I.Q, executive functioning and mental health in a subset of children in the study. Our study will have a highly accurate measure of cannabis use in pregnancy and be able to detangle the influence of other substances on child development, addressing the weaknesses in evidence published to date. It will provide important new evidence around the safety of cannabis use in pregnancy. It will also identify the risks of prenatal cannabis exposure to child cognitive development, social-emotional development and mental health in the long term, ensuring that children with prenatal cannabis exposure can receive the supports they need most to thrive.