Epilepsy de novo is rare in pregnancy. Epilepsy affects ~0.5% of women of child-bearing age so a unit with 3000 deliveries per year has ~15 pregnant epileptic women at any one time. Seizure rates worsen in most women having >1 seizure/month. Sleep deprivation in the last month of pregnancy may contribute to seizures. It is unusual for seizures to recur in pregnancy when preceded by a long seizure-free period.
Complications
Maternal
Risk of 3rd trimester vaginal bleeding. 1% convulse in labour.
Fetal:
- Haemorrhagic disease of newborn can occur with enzyme inducers (below).
- Congenital malformation (UK register suggests 5.9% affected with sodium valproate, 2.3% with carbamazepine, 2.1% with lamotrigine). Malformation is commoner if 2 anticonvulsants are used and with higher doses.
Fetal valproate syndrome
Signs: major organ system anomalies ± autism ± small ears, small broad nose, a long upper lip, shallow philtrum & micro/retrognathia.1
Cleft lip
Associated with maternal epilepsy only, the relative risk for a fetus having clefts compared to the non-epileptic population is 1.0 if the mother develops epilepsy after the pregnancy; 2.4 if she develops it after conception (but has no drugs); 4.7 if fetus is exposed to anticonvulsants. Phenytoin and phenobarbital cause clefts and congenital heart disease. Neural tube defects are commoner with valproate (& carbamazepine) so screen for these (p 10). Neurodevelopmental delay is seen with valproate, seen as lower verbal intelligence quotient (also seen in the offspring of those having frequent tonic clonic seizures in pregnancy.2
Management
Get expert help (refer to epilepsy specialist to optimize and monitor medication: only make antiepileptic changes on expert advice). Avoid trimethadione and paramethadione (both very teratogenic). Where anticonvulsants are needed keep the dose of the chosen drug as low as possible. Aim for 1 drug only. Give folic acid supplements, eg 5mg/24h PO from prior to conception. Give vitamin K1 20mg/24h PO to the mother from 36 weeks if she is taking enzyme inducers ie carbamazepine, ethosuximide, phenytoin, primidone, phenobarbitone (oxcarbazine and topiramate are subjects of debate).3 Screen for neural tube defects and heart disease if relevant (above). Treat status epilepticus as in the non-pregnant but monitor the fetus. It is associated with significant fetal and maternal mortality. Deliver in hospital with resuscitation facilities (1-2% epileptic women convulse in labour and the subsequent 48 hours)-and avoid early discharge. Give baby vitamin K 1mg IM at birth. If seizures are likely, to avoid dropping the baby during a seizure, advise changing the baby on mat on floor, and feeding sitting on floor supported by cushions, and only bath the baby with supervision. Mothers may breast feed (phenobarbital can cause drowsiness in the baby). Ask for review of epilepsy drugs postnatally eg at 12 weeks.
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