Carbamazepine

What is it?

Carbamazepine (Tegretol^®, Carbagen^®) is used to treat epilepsy, sometimes in combination with other epilepsy medicines. Carbamazepine is also used in the treatment of bipolar disorder, certain types of nerve pain, and during alcohol detoxification to control withdrawal symptoms.

Is it safe to take carbamazepine in pregnancy?

When deciding whether to use carbamazepine during pregnancy it is important to weigh up the potential benefits to your health and wellbeing against any possible risks to you or your baby, some of which may depend on how many weeks pregnant you are. Use of carbamazepine in pregnancy may sometimes be considered necessary to control epilepsy or bipolar disorder. Your doctor or specialist will help you make decisions about your treatment.

It is recommended that all women taking anti-epileptic medicines also take high dose folic acid (5mg/day) whilst trying to conceive and during the first trimester of pregnancy. High dose folic acid has to be prescribed by a doctor. For more information please see the folic acid bump leaflet.

What if I have already taken carbamazepine during pregnancy?

If you have taken or are taking any medicines it is always a good idea to let your doctor know that you are pregnant so that you can decide together whether you still need the medicines that you are on and, if so, to make sure that you are taking the lowest dose that works and only for as long as you need to.

It is very important that you do not suddenly stop taking carbamazepine as this could be dangerous. Do not make any changes to your medication without first talking to your doctor.

Because of the normal bodily changes associated with a progressing pregnancy, the dose of carbamazepine may need to be adjusted to ensure that symptoms remain well-controlled. Your doctor may offer ongoing monitoring to determine whether dose changes are required.

Can taking carbamazepine in pregnancy cause birth defects in the baby?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

A number of studies have suggested that carbamazepine use in pregnancy may increase the chance of a baby being born with a cluster of minor birth defects that includes permanently underdeveloped nails and subtly altered facial features (wide-spaced eyes, smaller, broader and flatter nose, tiny skin folds at the inner corners of the eyes [epicanthal folds], and the groove above the top lip [philtrum] being longer and smoother).

Five studies have investigated whether carbamazepine use in pregnancy increases the chance of the baby having a neural tube defect (defect of the brain or spine) such as spina bifida. Two of the older studies showed a possible link with spina bifida but three more recent studies showed that neural tube defects were not any more common in babies exposed in the womb to carbamazepine. Because the studies have produced different findings, more research is ideally required to determine whether carbamazepine use in pregnancy is linked to neural tube defects.

The available studies do not raise concern that carbamazepine use in pregnancy is linked to the baby being born with cleft lip and palate, heart defects, or hypospadias (where the opening of the penis is not in the usual place).

Can taking carbamazepine in pregnancy cause miscarriage or stillbirth?

The available data do not raise concern that carbamazepine use in pregnancy causes miscarriage or stillbirth. However, more research is ideally required before any links can be ruled out.

Can taking carbamazepine in pregnancy cause preterm birth or my baby to be small at birth (low birth weight)?

Studies of over 2,000 pregnant women do not raise concern that carbamazepine use causes preterm birth, and studies of almost 5,000 women have not shown a link with low infant birth weight.

Can taking carbamazepine in pregnancy cause other health problems in the child?

Withdrawal symptoms at birth (neonatal withdrawal)
Withdrawal symptoms are thought to occur when a newborn baby’s body has to adapt to no longer getting certain types of medicines through the placenta.

Carbamazepine works in a similar way to other medicines that are known to cause neonatal withdrawal, and there are case reports of withdrawal symptoms in newborn babies exposed in the womb to carbamazepine. Close monitoring of your baby for a few days after birth may therefore be advised if you have taken carbamazepine regularly in the weeks before delivery. Monitoring of your baby may be particularly important if you have taken carbamazepine in combination with other anti-epileptic medicines or medicines that act on the brain.

Bleeding problems in the newborn baby
Carbamazepine is similar to medicines that reduce the ability of blood to clot. No studies have specifically investigated whether bleeding problems are any more common in babies whose mothers took carbamazepine in pregnancy. However, because there is a theoretical risk of bleeding problems, it is currently recommended that all babies whose mother took carbamazepine in pregnancy receive an injection of vitamin K at birth to help protect against blood clotting problems.

Learning and behavioural problems
A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour. Because carbamazepine acts upon the brain, there have been concerns that its use in pregnancy may affect a baby’s brain development.

The majority of studies do not show that exposure to carbamazepine in the womb causes lasting alterations to a child’s learning and behaviour, and there is no evidence that carbamazepine-exposed children require more support at school. There is also no proof that children exposed in the womb to carbamazepine are more likely to be diagnosed with autism spectrum disorder or attention-deficit hyperactivity disorder.

While this is reassuring, ongoing research is required, particularly involving carbamazepine-exposed children as they grow older, before we can confirm that carbamazepine use in pregnancy will not affect a child’s learning and behaviour.

Will my baby need extra monitoring?

As part of their routine antenatal care most women will be offered a scan at around 20 weeks of pregnancy to look for birth defects and to check the baby’s growth. Women with epilepsy are likely to be more closely monitored during pregnancy to ensure that they remain well throughout and that their baby is growing and developing as expected. 

Because there is a possibility that carbamazepine taken in the first trimester might increase the chance of neural tube defects in the baby, your doctor may offer you the option of having more detailed anomaly scans. However, these are unlikely to detect the more subtle, minor defects that have been linked to carbamazepine exposure.

Carbamazepine can affect blood clotting, which may lead to bleeding problems in the baby after birth (see above). Pregnant women taking carbamazepine may therefore be offered vitamin K injections in the later stages of pregnancy to help prevent this.

If you have taken carbamazepine around the time of delivery your baby may require extra monitoring after birth because of the risk of neonatal withdrawal.

Are there any risks to my baby if the father has taken carbamazepine?

We would not expect any increased risk to your baby if the father took carbamazepine before or around the time you became pregnant.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org