Older parents - including mothers over 30 - are more likely to have children with autism

Mothers who conceive when they are over the age of 30 are more likely to have a child with autism. Kate Silverton, 43, is currently pregnant with her second child

Older parents are more likely to have children with autism, a study has found. Babies born to mothers who are over the age of 30 have an increased chance of developing the condition, the research revealed. And, for fathers, the risk grows steadily as they age, according to findings published in the International Journal of Epidemiology.



Professor Brian Lee and his colleagues at the Karolinska Institute in Sweden analysed the records of 417,000 children born between 1984 and 2003.
They compared parental age with other factors that could influence the risk of autism, such as family income, parent's psychiatric history and intellectual disability.
Professor Lee said: ‘The risk of having a child with Autism Spectrum Disorder (ASD) had a more complicated relationship to age in women than in men, whose risk of fathering a child with ASD increased linearly with age across their lifespan.
‘Among women giving birth before the age of 30, the risk of ASD in the child showed no association with age, it was simply very low.
‘But for babies born to mothers aged 30 and older, the chance of developing ASD rose rapidly.’

The professor said multiple mechanisms could account for the different patterns of risk, including environmental risk factors occurring in women over 30.‘Factors such as complications in pregnancy could also underlie the effect of mothers' ages on a child's ASD risk but not a paternal age effect ASD,’ he explained.

However, Professor Lee said the overall risk for couples thinking of starting a family remained low. 

He said: ‘The absolute risk of having a child with ASD is still approximately one in 100 in the overall sample, and less than two in 100 even for mothers up to age 45.’

The research supports another recent study which found the children of older fathers are more likely to develop autism and psychiatric disorders.

The study, published in the JAMA Psychiatry journal, revealed children born to fathers over the age of 45 are three and a half times more likely to develop autism than those born to men in their early 20s.

It also revealed that there was a 24-fold increased risk of bipolar disorder and a 13-fold high risk of ADHD in children born to older fathers.

Among well-known older parents are Simon Cowell, 54, who recently had a son and Kate Silverton, 43, who is due to give birth in a matter of weeks.