Curtin University study reveals mother’s cannabis use triples risk of disruptive behaviour in children

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 revealed. The study, published in Psychiatry Research, analysed data from more than 222,600 Australian mothers and children revealing cannabis use during pregnancy and while breastfeeding significantly increased the risk of developing disruptive behavioural conditions. These conditions include oppositional defiant disorder — a pattern of uncooperative, defiant, and hostile behaviour towards peers and authority figures — and conduct disorder which involves aggressive, antisocial, and destructive actions. Cannabis use during pregnancy increased the risk of these disorders by 3.56 times while postnatal use increased the risk by 2.95 times. Male children were more likely to be diagnosed with disruptive behavioural disorders than females. With an estimated one in five Australian pregnant women using cannabis, Curtin lead researcher Abay Tadesse called 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 and conduct disorder,” he said. “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,” she said. “This research provides critical evidence to help shape health policies aimed at minimising harm. “While intervention strategies are essential, further genetic research is also needed to better understand the link between maternal cannabis use and childhood behavioural disorders.”