Epilepsy medicines and pregnancy

Carbamazepine use during pregnancy increases the risk of physical birth defects. If 100 women take carbamazepine during their pregnancy, 4 to 5 of the babies will be born with physical birth defects. This compares with 2 to 3 out of 100 in the general population.

The available information does not suggest an increased risk of learning and thinking difficulties in children whose mothers took carbamazepine during pregnancy.

It is not possible to confirm or rule out whether carbamazepine affects the growth of the baby in the womb. This is because the available evidence is inconsistent.

Some research suggests that clobazam may slightly increase the risk of a baby being born with physical birth defects.

However, the research that is available does not allow firm conclusions to be reached. So, the risk of harming a baby cannot be confirmed or ruled out.

The risks of taking gabapentin during pregnancy are not yet fully understood. The MHRA was not able to make any firm conclusions about its safety in pregnancy.

Lamotrigine is one of the safer medicines to use during pregnancy. Research suggests that it does not increase the risk of physical birth defects compared with the general population.

There is less information about whether taking lamotrigine in pregnancy causes learning or thinking difficulties in children. The limited information available does not suggest an increased risk compared to the general population, but the possibility of an increased risk cannot be ruled out.

Information suggests that using lamotrigine during pregnancy does not affect a baby’s growth in the womb.

Levetiracetam is one of the safer medicines to use during pregnancy. Research suggests that it does not increase the risk of physical birth defects compared with the general population.

There is less information about whether taking levetiracetam in pregnancy causes learning or thinking difficulties in children. The limited information available does not suggest an increased risk compared to the general population, but the possibility of an increased risk cannot be ruled out.

Information suggests that using levetiracetam during pregnancy does not affect a baby’s growth in the womb.

There is only limited information about the risk of birth defects with this medicine. This means an increased risk of birth defects cannot be ruled out.

The MHRA was also not able to make any firm conclusions about whether this medicine may increase the risk of learning and thinking difficulties, or affect growth in the womb.

Phenobarbital use during pregnancy increases the risk of physical birth defects. If 100 women take phenobarbital during their pregnancy, 6 to 7 of the babies will be born with physical birth defects. This compares with 2 to 3 out of 100 in the general population.

Phenobarbital taken during pregnancy also increases the risk the child may have difficulties with learning and thinking ability. Although the exact risk is not known, it is not as high as for valproate, which causes difficulties in 30 to 40 out of 100 children.

Taking this medicine during pregnancy also increases the risk of the baby being born smaller than expected compared with the general population.

Phenytoin use during pregnancy increases the risk of physical birth defects. If 100 women take phenytoin during their pregnancy, 6 of the babies will be born with physical birth defects. This compares with 2 to 3 out of 100 in the general population.

Phenytoin taken during pregnancy also increases the risk the child may have difficulties with learning and thinking ability. Although the exact risk is not known, it is not as high as for valproate, which causes difficulties in 30 to 40 out of 100 children.

It is not possible to confirm or rule out whether phenytoin affects the growth of the baby in the womb. This is because the available evidence is inconsistent.

In April 2022 the MHRA published a drug safety update for pregabalin. A study of more than 2,700 pregnancies suggests that taking pregabalin during pregnancy may slightly increase the risk of a baby being born with birth defects.

The MHRA says that people should use effective contraception when taking pregabalin, and avoid taking it during pregnancy unless the benefits outweigh the risks.

The MHRA introduced new rules in June 2024 about taking topiramate. This is after an evidence review of the risks of taking topiramate in pregnancy for an unborn baby.

The rules have been introduced to make sure more people understand the risks of taking topiramate in pregnancy.

These rules are different to the rules for taking sodium valproate.

What are the risks of taking topiramate in pregnancy?

Topiramate use during pregnancy increases the risk of physical problems for the baby. These are sometimes called birth defects. One example might be a cleft lip or palate. This is where there is a split in the upper lip or roof of the mouth. It happens if a baby’s face doesn’t fully join together in the womb.

If 100 people take topiramate during their pregnancy, 4 to 9 of the babies could be born with physical birth defects. This compares with 1 to 3 out of 100 in the general population.

Taking topiramate during pregnancy also increases the risk of the baby being born smaller or weighing less than expected.

If 100 people take topiramate during pregnancy, 18 out of 100 babies could be born smaller or weigh less than expected. The same study found that 5 out of 100 babies are born smaller than expected in the general population.

Children might also have an increased risk of problems with learning and development. This could be:

• Autism spectrum disorders (ASD)
• Attention deficit hyperactivity disorder (ADHD)
• Learning difficulties

What are the rules for taking topiramate?

If you are able to become pregnant, doctors must only prescribe you topiramate if you’re on the Pregnancy Prevention Programme:

• Doctors can only prescribe topiramate if you are on effective contraception. This is to lower the risk of harm to an unborn baby. Topiramate can affect how well some types of contraception work. More information can be found on our contraception page
• Your specialist will talk to you about the risks and benefits of taking topiramate. They may discuss switching medicines. Your specialist should review your medicine at least once a year. At these appointments they will complete an annual risk awareness form with you. They may ask you to do a pregnancy test to check you’re not pregnant
• Your doctor should give you a copy of the patient guide and patient card. These explain the guidance and your risks

What if I’m pregnant or planning a baby?

It’s really important not to stop taking your epilepsy medicines before speaking to a doctor.

You should speak to your specialist urgently if you’re pregnant and taking topiramate. They will be able to discuss your options with you.

If you are planning to have a baby, speak to your specialist before you become pregnant. This is so any changes to your medicines can happen a long time before you become pregnant. You should keep taking contraception until you have discussed your options with a doctor.

What if my child is taking topiramate?

If your child is a girl, a doctor should explain the risks of taking topiramate to you and your child. They should do this even if they have not started their period yet. This is so you’re prepared for the future. A specialist should review your child’s medicine each year. They will complete the risk awareness form with you.

Your child should see a specialist when they first start their period. They will help to decide whether topiramate is still the right medicine to take.

We understand that the new rules can be worrying and confusing. You can find out more information about the risks of topiramate from the government website and patient guide. You can also speak to your specialist, GP or epilepsy specialist nurse if you have any questions.

Epilepsy Action will continue to update our website with the latest information.

Medicines containing valproate (sodium valproate and valproic acid) can seriously harm the unborn baby if taken during pregnancy. If 100 women take valproate medicines during their pregnancy, about 10 of the babies will be born with physical birth defects. This compares with 2 to 3 out of 100 in the general population.

About 30 to 40 of the 100 children will go on to have lifelong difficulties with learning and thinking abilities, including autism (also called neurodevelopmental disorders).

For up-to-date information about valproate for women who could become pregnant, visit our webpage or call the Epilepsy Action Helpline on 0808 800 5050.

More research is needed to understand if zonisamide use during pregnancy increases the risk of birth defects.

More research is needed to understand if zonisamide use during pregnancy increases the risk of a child having thinking or learning difficulties.

Zonisamide use during pregnancy increases the risk of the baby being born smaller than expected compared with the general population.

The medicines listed below are less commonly prescribed in the UK. The MHRA found there is not enough information on their use in pregnancy to make any conclusions about their safety when used during pregnancy. This means the risk of harming a baby cannot be confirmed or ruled out.