Children born to obese mothers have an increased risk of behavioural and neuropsychiatric conditions, including autism and ADHD.
A review and meta-analysis of more than 3.6 million mother-child pairs across 42 studies found that obesity during pregnancy increased the risk of ADHD in children by 32 per cent, doubled the risk of developing autism in children and increased the risk of conduct disorders by 16 per cent.
The University of South Australia study was conducted in partnership with Curtin University, Monash University, the SA Health and Medical Research Institute and a team of national institutions.
It also found that being overweight or obese before pregnancy was linked with an increased risk of ADHD, autism, conduct disorder and psychotic disorder as well as a 30 per cent increased risk in both externalising symptoms, and peer relationship problems.
The study provides insights into the long-term impact of maternal body weight on child mental health, lead researcher UniSA's Bereket Duko said.
"Maternal obesity has long been associated with a range of adverse perinatal outcomes, including preterm birth, low birthweight, stillbirth, and it is also linked with macrosomia, or high birthweight," Dr Duko said.
"We examined maternal overweight and obesity before and during pregnancy, finding that both are significantly linked with psychiatric and behavioural problems in children later in life, specifically ASD, ADHD and peer relationship problems.
In Australia, about one-in-150 people have autism spectrum disorder while more than eight per cent of children aged four-to-11 have been diagnosed with ADHD.
"While further research is needed to explore the biological mechanisms underlying these associations, the findings do stress the need for health interventions that promote healthy living and weight among parents to be," Dr Duko said.
