Case Study Reports: Epilepsy in Pregnancy

EPILEPSY IN PREGNANCY

History

A 24-year-old woman attends for pre-pregnancy counselling. Her general practitioner (GP) referral letter is shown.

Dear Doctor

Please could you see and advise this young woman who wishes to start a family in the near future?

She was diagnosed with grand mal epilepsy when she was 12 and has been on medication since then. She was initially under a paediatric neurologist but for the last 6 years has been under my care at the practice. Her current treatment regime includes sodium valproate, phenytoin and lamotrigine. She last had a fit around 1 month ago.

She recently married and is keen to start a family as soon as possible. I would be grateful if you could see her to discuss the management of any pregnancy. She has never been pregnant before.

Yours sincerely

Questions

·             What specific risks are there in pregnancy for this woman?

·              How should she be managed?

Answer:

·              The incidence of epilepsy in women of child-bearing age is approximately 1 in 150.

·              The risks of epilepsy in pregnancy can be divided into risks to the mother and to the fetus.

Risks to the mother

Increased plasma volume causes reduced drug levels and a possible increase in fits. Other causes of increased fit frequency include excessive tiredness and hyperemesis. Some women also decide to stop their medication because of fears of adverse effects on the baby, although this may actually increase the risk to the baby as a result of a higher like- lihood of prolonged fits.

Risks to the fetus

There is an increased risk of congenital abnormality due to antiepileptic drugs (7 per cent risk for one drug, with risk increasing with multiple drugs). The risk probably applies simi- larly to all antiepileptic medications used.

There is also an intrinsic increased risk of epilepsy in the offspring of an epileptic mother, and during the pregnancy the fetus is also at risk of fetal hypoxia from uncontrolled maternal epilepsy.

Management principles

Pre-pregnancy

·              Refer for neurology opinion and minimize the number of drugs, aiming for a single drug regime.

·              If no fits have occurred for at least 2 years consider stopping all medication.

·              Advise the woman to continue her medication during pregnancy, as having an increased number of fits is likely to increase the risk of fetal hypoxia.

·              Prescribe preconceptual folic acid (5 mg daily rather than 400 μg) to minimize the risk of neural tube defects and prevent folate deficiency seen with antiepileptic regimes.

Antenatal

·              Plan for joint medical and obstetric care.

·              Monitor plasma levels of anticonvulsant regime (levels are likely to diminish due to increased plasma volume).

·              Advise the woman to take showers instead of baths to minimize the risk of drowning if a fit occurs in the bath.

·              Arrange detailed anomaly scan and a fetal echocardiography at around 18–20 weeks for cardiac abnormalities.

·              Start vitamin K from 36 weeks’ gestation, to correct any potential clotting deficiency from the inhibition of clotting factor production by anticonvulsants and thus reduce the chance of fetal bleeding (e.g. intraventricular haemorrhage). The baby should also receive intramuscular (rather than oral) vitamin K at birth.

·              There are no specific differences in labour management from non-epileptic women.

Postnatal

·              Anticonvulsant therapy is not a contraindication to breast-feeding.

·              Decrease medication doses as maternal physiology returns to normal.

·              Adequate social support is vital and plans need to be made for safe care of the infant (due to the risk of fits in the mother).