A new study has discovered an increased risk of autism in children born to mothers who are overweight before they become pregnant, according to a report in the Daily Mail.

Researchers from the Virginia Commonwealth University found that obese mothers had a 36 per cent higher risk of having a child on the autistic spectrum.

The risk was 17 per cent higher in overweight women, they add.

The university says the results highlight future risk as the general population on average becomes more overweight.

In the UK, 62 per cent of adults are considered overweight, while 28.1 per cent of adults are considered clinically obese, with almost six in 10 women in the UK classed as obese or overweight.

Obesity is already known to be a major risk to personal health, but the effects it may have on unborn children are widely under-researched.

Professor Dr Bernard Fuemmeler of the Virginia Commonwealth University said: “Prenatal exposure to environmental toxins, stress and nutrition have all been linked to neurodevelopmental outcomes in children.

“Of note, the increase in prevalence of neurodevelopmental problems has also been paralleled by an increase in prevalence of obesity in society.

“This parallel, along with preclinical data linking high-fat diet and pre-pregnancy obesity to errant brain and behavioural development in offspring, have led to speculation that there may be a link between these two recent trends.

“Correspondingly, there has been growing attention to maternal weight status, either pre-pregnancy weight or excess gestational weight gain, on children’s neurodevelopmental outcomes.”