Case 55: Epilepsy in pregnancy

 

Case 55: Epilepsy in pregnancy

CASE 55: EPILEPSY IN PREGNANCY

History

A 24-year-old woman attends for prepregnancy counselling. Her general practitioner 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?100 Cases in Obstetrics and Gynaecology

148

ANSWER 55

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 likelihood

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 similarly 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

Prepregnancy

• Refer for neurology opinion and minimize the number of drugs, aiming for a single

drug regime.

• 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.

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

• Prescribe preconceptual folic acid (5 mg daily rather than 400 mg) 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).Case 55: Epilepsy in pregnancy

149

KEY POINTS

• Prepregnancy fits should be well controlled, aiming for a single drug regime.

• Epileptic medication is associated with an increased risk of congenital abnormality

but the risk to the mother and baby of stopping medication usually takes priority

over the risk of fetal abnormality.

• Drug compliance during pregnancy must be emphasized.