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Effect of pregnancy on epilepsy

It is impossible for anybody to predict what effect pregnancy will have on epilepsy. Roughly 50% of patients see no change in the seizure frequency. Of the remainder, some will experience more seizures and some fewer.

Pregnancy complications associated with epilepsy

The aim of managing epilepsy in pregnancy will be to prevent seizures, as these could lead to injury to you and may cause a late miscarriage or premature delivery, with consequent loss of your baby.

Apart from that, there is known to be a slight increase in the risk of bleeding in pregnancy. Bleeding, when it occurs, is usually light and painless. It very rarely threatens the well-being of the pregnancy.

Epilepsy does not make you more prone to develop other pregnancy-related problems, such as pre-eclampsia.

Maternal epilepsy and the baby

There is an increased risk (compared to the general population) of major malformations, especially those of the skull, mouth or heart. Most of these can be detected by ultrasound scanning, optimally at around eighteen to twenty weeks of gestation. This needs to be taken in perspective: Nine out of ten (90%) babies born to epileptic mothers are free of any malformations.

Can the risk of malformations be reduced or eliminated by stopping anticonvulsant medication?

This would not work. This is because the increase in the risk of fetal malformations is inherently there by virtue of the mother having epilepsy. This background risk remains the same, whether she is on anticonvulsant medication or not. It is probably more important to concentrate on the positive aspect that the baby has a 90% chance of being completely normal.

Effect of epilepsy medication on the risk of malformation

Broadly speaking, medication taken to control epilepsy does increase risk of fetal anomalies. However, there is a wide variety of anticonvulsant medication and new ones are coming on the market all the time.

Of the traditional anticonvulsants, carbamazepine (Tegretol®, Carbagen®SR) is considered to be the safest, in relative terms. It is, however, not completely free of side-effects to the fetus, and may occasionally cause defects, mostly minor.

Phenytoin (Epanutin®) may cause some defects of the skull bones, digits and occasionally may have long-term consequences including mental retardation, with learning difficulties. It should be stressed here that all these are quite uncommon.

Stopping anticonvulsant medication when planning to conceive

The issue of continuing with medication during pregnancy is rather complex.

For the majority of women with epilepsy, continuing with medication is not only desirable but imperative. In carefully selected cases, where there have been no seizures for at least two years, an attempt to stop anticonvulsants in the preconception period could be considered. This has always got to be done in full consultation with the individual’s doctor. If the woman remains free of seizures, she could be managed by observation alone.

Unfortunately, around 30% of all patients who try this strategy have a recurrence of seizures and have to go back on medication.

It is certainly considered unwise to adopt this strategy if you are already pregnant. In this case, medication should be continued.

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