A drug to treat epilepsy and bipolar disorder has been responsible for "severe malformations" in up to 4 100 children in France since 1967, according to a study.
Women who took valproate during pregnancy to treat epilepsy were four times more likely to give birth to babies with malformations, said the report by French health authorities.
Bipolar women taking the drug – marketed around the world as Depakine, Depakote, Stavzor and other names – were twice as likely to give birth to children with major defects.
Defects attributed to the drug included spina bifida – in which the spinal cord does not form properly – as well as defects of the heart and genital organs.
The risk of autism and developmental problems was also found to be higher.
The report by the national agency for the safety of medicines and the national health insurance administration said the drug has been responsible for "severe malformations" in between 2 150 and 4 100 children in France since it was first marketed in the country in 1967.