One in ten (11 per cent) women who are currently taking the epilepsy medicine valproate are unaware of the possible risk of birth defects if taken in pregnancy, according to a poll.
And 18 per cent do not know that, when taken in pregnancy, the medicine could also cause learning and developmental delays in children, according to a poll of 751 British women and teenagers who are taking the medication.
The poll comes ahead of the publication of the Independent Medicines and Medical Devices Safety Review, which is to be published later this week.
The review will examine sodium valproate as well as two other controversial medical treatments - vaginal mesh and the hormone pregnancy test Primodos.
It has been estimated that one in ten babies born to women who take sodium valproate during pregnancy could be born with birth defects. And up to 40 per cent risk developmental issues and learning disabilities.
There have been significant pushes for women of childbearing age to be made aware of the dangers of the drug for unborn babies.
But the charities Epilepsy Action, Epilepsy Society and Young Epilepsy raised concerns that many women are still in the dark about the issue.
Their poll also found that 44 per cent of participants had not discussed the risks of taking the medicine with their health professionals in the past 12 months.
And 41 per cent of the respondents taking valproate said they had signed an annual risk assessment form - which declares they have discussed and are aware about the risks of the medication and have discussed alternative treatment courses where necessary.
Simon Wigglesworth, deputy chief executive of Epilepsy Action, said: “It’s simply unacceptable that some women with epilepsy are still in the dark about the dangers of taking valproate in pregnancy.
“Just one woman unaware of the serious impact it could have on her unborn child is one woman too many.
“With a wealth of resources now available for health professionals to facilitate conversations, there is just no excuse for not explaining the risks to every woman taking valproate. Change needs to happen now to prevent babies being needlessly harmed and the devastating, lifelong impact this has on families.”