Expectant mothers who have a flu or fever in pregnancy increase the risk of their child having autism by up to 300 per cent, a study has claimed.
The Mailman School of Public Health at Columbia University in New York City, which published the study, said the link was strongest with fevers reported during the second trimester.
It said the number of fevers contracted also correlated with risk of autism, with mothers having three or more increasing the risk by up to 300 per cent.
It added that just one fever can heighten the risk by 34 per cent.
Researchers suggested that the bug or virus causing the fever could impair the growth of cells in the developing foetus.
Dr Maddy Hornig, co-author of the report, said: “Our results suggest a role for gestational maternal infection and innate immune responses to infection in the onset of at least some cases of autism spectrum disorder.”
Co-author Professor Lipkin added: “Future work should focus on identifying and preventing prenatal infections and inflammatory responses that may contribute to autism spectrum disorder.”
Current guidance suggests that women should receive the flu vaccine during pregnancy, as this is the time when women are most susceptible.