2:15pm (UK)

By Victoria Ward, PA, in New York

Expectant mothers suffering from allergies or asthma could be up to 50% more likely to have an autistic child, according to new research.

The increase in autism is most likely if the mother’s symptoms are diagnosed in the second trimester of pregnancy, United States scientists found.

The study, published in the Archives of Paediatric and Adolescent Medicine, found no statistical link between autism in children and 44 autoimmune diseases in mothers, including rheumatoid arthritis, diabetes and multiple sclerosis.

But the exception was psoriasis, which doubled the risk of autism, as did asthma and allergies.

Researchers at the Kaiser Permanente’s Division of Research in Oakland, California note that the numbers of those with asthma and allergies, as well as the incidence of autism, have risen over the past few decades.

Autism is a mysterious condition that affects around six in 1,000 children, mostly boys, and is associated with diminished social skills and communication.

The study looked at 88,000 children born in Northern California between January 1995 and June 1999.

Of the group, 420 children between three and seven years old were found to have autism.

Each autistic child was matched with five children who did not have autism but who were of the same sex and born the same year and in the same hospital.

The report suggests there may be a common underlying genetic cause to conditions such as asthma and autism.

Scientists stressed this was the first study to link a mother’s allergies to autism and that more research must be done.

They caution that the risk of autism is still less than 1% in children of women with asthma during pregnancy.