Australian study shows weight during pregnancy correlates to neurological disorders

A study linking obesity and overweight in mothers during pregnancy to neurological disorders could prompt further study of brain development in utero.

Women experiencing overweight and obesity are at a heightened risk of giving birth to children with neurological disorders, an Australian study has shown. Picture: AAP

An Australian study has found mothers who are overweight or obese before and during pregnancy place their children at higher risk of autism, ADHD and associated behavioural conditions.

Epidemiological research by the University of South Australia analysed 42 prior population studies from across the world, examining the health of 3.6 million mothers and children, to find the correlation between weight during pregnancy and post-natal neuropsychiatric conditions.

The analysis, led by epidemiologist Bereket Duko, showed children born to mothers who are obese during pregnancy have a 223 per cent higher chance of developing autism than the norm, ADHD was 32 per cent higher and conduct disorder was 16 per cent higher.

The study showed unhealthy maternal weight before pregnancy also raised the neurological disorder risk, even if it is regulated after conception. It was also found to impact peer relationships, inattention and aggression.

However, there was no association found between maternal weight and anxiety, personality disorders, eating disorders or sleep disorders.

Because the study was based purely on data analysis, it does not indicate that maternal weight causes neurological disorders, only that it is correlated with them.

University of South Australia researchers also suggested future research would need to include genetic analysis and take into account factors associated with obesity such as socio-economic status, family history, environment and stress.

An estimated 0.08 per cent of Australia’s population is autistic, although the rate of diagnosis has risen in recent years with greater societal recognition of the condition. ADHD is slightly more frequent, occurring in an estimated 8 per cent of children aged four to 11 and up to 6 per cent of adults, according to the Australian and New Zealand Journal of Psychiatry.

University of South Australia epidemiologist Bereket Duko.

“Given the rising global obesity rates among women of reproductive age, and the growing numbers of children identified with neurodiverse conditions, it’s important that we acknowledge the potential long-term consequences of (these findings),” Dr Duko said.

Dr Duko speculated that obesity’s common comorbidity with gestational diabetes and high blood pressure could be factors, given they were both independently found to have raised the risk of neurological and behavioural disorders in children.

He also suggested inflammation caused by hormone imbalances and complicated metabolism may hamper brain development in utero, explaining the findings.

“We are suggesting future studies should comprehensively address the potential confounders,” Dr Duko said. “It is a limitation of our study that potentially may overestimate or underestimate the effect that is reported.

“If a study is able to adjust for those confounders, that study could potentially produce good causal inferences.”

Of the 42 studies analysed, 16 detailed the effect of maternal weight on ADHD, 11 on mood and anxiety disorders, 10 on internalising behaviours such as social withdrawal, seven on autism, and six on peer relationship problems.

Research was conducted in collaboration with Curtin University, Monash University, the South Australian Health and Medical Research Institute and the Centre of Research Excellence Health in Preconception and Pregnancy.

Dr Duko hoped in future to use machine learning to do large-scale analysis of prior studies to create a more complete view of causes and outcomes from pregnancy complications.

He hoped the study would prompt further efforts to curb overweight and obesity among women trying for pregnancy.

“Public health efforts that target improving maternal health could help mitigate some of the risks,” he said.

“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.”

The causes of autism are varied and still being researched. It is highly heritable but found to be influenced by outside factors such as air pollution, heavy metal and polycarbonate plastic exposure during pregnancy, as well as prenatal stress, and fetal drug and alcohol exposure.