Children exposed to their mother's cannabis use during pregnancy and after birth are three times more likely to develop behavioural problems, new Curtin University research has found.

Published in Psychiatry Research, the study, "Maternal cannabis use disorder and offspring behavioural outcomes: findings from a linked data cohort study," analyzed data from more than 222,600 Australian mothers and children, revealing maternal cannabis use disorder (CUD) during pregnancy and the postnatal period significantly increased the risk of childhood disruptive behavioural disorders.

Lead researcher Abay Tadesse, from Curtin's School of Population Health, said the findings highlighted the need for interventions targeting cannabis use among reproductive-age women.

"We found children of mothers with cannabis use disorder were at a significantly higher risk of developing behavioural issues such as oppositional defiant disorder (ODD) and conduct disorder (CD)," Mr. Tadesse said.

"Our research showed maternal cannabis use during pregnancy increased the risk of disruptive behavioural disorders by 3.56 times, while postnatal use increased the risk by 2.95 times.

"With an estimated one in five Australian pregnant women using cannabis and disruptive behavioural disorders on the rise, our findings underscore the growing public health concern around cannabis use."

Professor Rosa Alati, the Head of Curtin's School of Population Health, said the study highlighted the lasting impact of maternal cannabis use on children's mental health.

"Cannabinoid ingredients can cross the placenta and enter breast milk, potentially affecting brain development. This research provides critical evidence to help shape health policies aimed at minimizing harm," Professor Alati said.

"While intervention strategies are essential, further genetic research is also needed to better understand the link between maternal cannabis use and childhood behavioural disorders."

This study identifies maternal cannabis use as a significant risk factor for childhood disruptive behavioural disorders, acknowledging that these associations are also likely to be influenced by a range of genetic, environmental and social factors.

More information: Abay Woday Tadesse et al, Maternal cannabis use disorder and offspring behavioural outcomes: findings from a linked data cohort study, Psychiatry Research (2025). DOI: 10.1016/j.psychres.2025.116404