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21st June 2023
Pregnancy
In those with epilepsy who are pregnant, there is a huge and understandable concern about AEDs harming the unborn baby. Therefore, it is essential to be aware of the potential harms and the rates of harmful effects for each of the common AEDs, so one can counsel a woman on the risks and come to a joint decision on which AED to prescribe. A change in AED might need to be made. Overall, it is essential to emphasise the importance of compliance during pregnancy, as the risk of harm to baby from an epileptic seizure is more likely than the risk of harm from taking the AED.
The Medicines and Healthcare products Regulatory Agency has produced updated advice on AEDs in pregnancy following a comprehensive safety review based on all evidence of the effects of AEDs on the mother and the baby.
The following AEDs have evidence-based harmful effects according to the table below. If the AED is not listed in the table, then either the evidence shows the AED does not increase the risk of the harmful effect, or there is not enough evidence to draw a conclusion either way.
| Harmful effect | Anti-epileptic drugs |
|---|---|
| Congenital malformations |
|
| Neurodevelopmental disorders |
|
| Intrauterine growth restriction (IUGR) |
|
The table below summarises the effect of pregnancy on serum levels of the AED according to studies.
| Anti-epileptic drug | Effect on levels during pregnancy | Monitoring |
|---|---|---|
| Levetiracetam | Decrease in levels during pregnancy – up to a 60% decrease in the third trimester. | Take a baseline levetiracetam level before pregnancy and monitor the levels during and after pregnancy. Adjust the doses accordingly. |
| Lamotrigine | Decrease in levels during pregnancy. Seizure control can be lost as a result. | Take a baseline level before pregnancy and monitor the levels during and after pregnancy. Adjust the doses accordingly.
Lamotrigine levels can increase significantly after birth. There is an increased risk of dose-related adverse events. |
| Carbamazepine | Not enough evidence on whether carbamazepine levels change during pregnancy. | Recommended to monitor the levels of the 10-monohydroxy derivative (MHD), the active metabolite of carbamazepine, to ensure seizure control is maintained. |
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