CKS Clinical solutions - Epilepsy and pregnancy

THE CASE: A 30-year-old woman with epilepsy explains that she would like to start a family and asks for advice regarding managing her epilepsy.

Spina bifida: AEDs may cause neural tube defects (Photograph: SPL)
Spina bifida: AEDs may cause neural tube defects (Photograph: SPL)

What advice should I give?
Explain that although most women with epilepsy have a normal pregnancy, the risk of complications during pregnancy and labour is higher than for women without epilepsy.

The risks associated with inadequate seizure control may be more detrimental to the foetus than the use of antiepileptic drugs (AEDs).

There is an increased risk of seizures in the children of parents with epilepsy, but the probability that a child will be affected is generally low.1-3

What is the risk to the foetus with AEDs?
The overall risk of a major foetal abnormality in any pregnancy in the general population is about 2 per cent.

This risk is increased in women taking AEDs and is dependent on the individual drug, the dose and the number of AEDs taken. For women taking a single AED:1,4

  • The risk with carbamazepine is 2.2 per cent.
  • The risk with lamotrigine is about 3 per cent (depending on dose).
  • The risk with sodium valproate is 5-9 per cent (depending on dose).

The risk is increased with an increasing number of AEDs taken, and may be up to 24 per cent in women taking four AEDs.

Should I refer to a specialist?
Refer a woman taking AEDs to an epilepsy specialist before she becomes pregnant to discuss the relative risks and benefits of adjusting her medication. Withdrawal of treatment or a dose reduction if seizures have been well controlled, or switching to AEDs that are less harmful to the foetus, may be considered.1-3

How do I manage the woman while awaiting a referral?
Advise the woman to continue using effective contraception until she has seen the specialist.

If she becomes unexpectedly pregnant, advise her to continue her AEDs and make an urgent appointment. Prescribe folic acid 5mg daily and continue this throughout the first trimester of pregnancy.

How do I manage her if she becomes pregnant?
Advise the woman to continue her AEDs and refer her urgently for review by an epilepsy specialist. Encourage her to notify the pregnancy, or allow her clinician to notify the pregnancy, to the UK Epilepsy and Pregnancy Register (www.epilepsyandpregnancy.co.uk).2

Evidence
The recommendation to inform women about the risks of AEDs in pregnancy and refer for a specialist review is based on expert advice.1-3

The risk of major malformations has been examined by a prospective study from the UK Epilepsy and Pregnancy Register of 3,607 pregnancies.4

The recommendation to prescribe folic acid is based on evidence of its effectiveness at reducing the incidence of neural tube defects. Encouraging women with epilepsy who become pregnant to notify the UK Epilepsy and Pregnancy Register is based on NICE.

References
1. SIGN. Diagnosis and management of epilepsy in adults: A national clinical guideline. 2003.

2. NICE. The epilepsies: The diagnosis and management of the epilepsies in adults and children in primary and secondary care. CG20 2004.

3. SIGN. Diagnosis and management of epilepsies in children and young people. 2005.

4. Morrow J, Russell A, Guthrie E et al. J Neurol Neurosurg Psychiatry 2006; 77(2): 193-8.

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