Up to 4,100 children in France suffered severe birth defects after their mothers took the epilepsy drug sodium valproate, the French health authorities said yesterday (Thurs).

The drug, also prescribed in France for bipolar disorder, was taken by up to 100,000 pregnant women between 1967 and 2016, according to a joint report by the French National Agency for the Safety of Medicines (ANSM) and the national health insurance body.

It is also believed to have been taken by thousands of pregnant women in the UK.

Marketed in France under the brand name Depakine for epilepsy and Depakote or Depamide for bipolar disorder, it is one of the most effective and widely prescribed drugs for controlling epileptic seizures. Its British equivalent is Epilim.

Parents of the children affected say the French government and the drug’s manufacturer, Sanofi, were too slow to warn of the drug’s side-effects although the risks to foetuses were known by the early 1980s.

Sanofi, was not immediately available for comment.