They studied 632 children and found the mothers of those who took valproate during pregnancy were seven times more likely to have a child with autism than mothers who did not.
Of the children whose mothers took epilepsy drugs while pregnant, 64 were exposed to valproate, 44 to lamotrigine, 76 to carbamazepine and 65 to other epilepsy drugs. Nine were diagnosed with autism and one showed symptoms of the disorder. The children were tested at one, three and six years old.
The ongoing study was conducted by the Liverpool and Manchester Neurodevelopment Group.
‘More research needs to be done since these are early findings,’ said study author Gus Baker, from the University of Liverpool.
‘However, women who take valproate while pregnant should be informed of the possible risks of autism and are encouraged to discuss them with their doctor,’ he said.