Women with Epilepsy: A Handbook of Health and Treatment Issues (Chapter 19)

Pregnancy risks for the woman with epilepsy (Excerpt)

Mark Yerby and Yasser Y. El-Sayed

Reproductive health care is important for every woman. For a woman with epilepsy, regular appointments with her neurologist do not replace the essential visits to her obstetrician/gynecologist. Especially important is an understanding of how epilepsy affects a woman’s reproductive health as well as how her gynecological and obstetrical health affects her epilepsy.

Most women with epilepsy can become pregnant and have healthy children. However, their pregnancies are subject to a greater risk of complications, difficulties during labor, and a risk of adverse outcomes.

During pregnancy, one-quarter to one-third of women have more frequent seizures. Whether a woman will have more seizures appears to be unrelated to her seizure type, how long she has had epilepsy, or her seizure frequency in a previous pregnancy. Although an association was found between seizure frequency prior to pregnancy and increased seizures during parturition in one study, these observations have not been verified by other investigators.

A variety of hypotheses have been proposed to explain the increase in seizure frequency seen during pregnancy. Blood levels of antiepileptic drugs (AEDs) decline as pregnancy progresses, even if the AED dose is held constant or even increased. Yet, blood levels of AEDs tend to rise after delivery (postpartum). Whereas reduction of plasma drug concentration is not always accompanied by more frequent seizures, virtually all women with increased seizures in pregnancy have drug levels that are below the standard therapeutic range. There are several reasons why AED levels may drop during pregnancy, such as poor absorption from the gastrointestinal tract, a reduction in the blood proteins to which AED molecules attach, and increased clearance of the AED from the body because of liver metabolism and clearance by the kidneys. The rate of clearance appears to be greatest during the third trimester. Pregnancy-related weight gain may also cause drug levels to fall.

Sometimes, drug levels fall because of poor compliance with the recommended medication schedule. In one prospective study, it was found that more than one-third of pregnant women with epilepsy had more frequent seizures during pregnancy. Upon careful questioning, it was found that 68% of these women were not taking their medication as prescribed. In a Japanese study, seizures were more frequent in 27% of the women. One-half of these women were deliberately not taking as much medication as advised by their doctors because they were concerned about the effects the AEDs might have had on their children. To make certain that AED blood levels are kept within the most desirable range, many physicians recommend frequent monitoring of AED free levels.

It is important to maintain good seizure control during pregnancy, particularly the control of tonic-clonic seizures (grand mal seizures or convulsions). Seizures during the first trimester (the first 3 months of pregnancy) appear to increase the risk of congenital malformations. Generalized tonic-clonic seizures place both mother and fetus at risk for hypoxia and acidosis as well as for injury from blunt trauma. Canadian researchers have found that maternal seizures during gestation increase the risk of development delay. Although rare, stillbirths have occurred following a single generalized convulsion or series of seizures. Status epilepticus (i.e., prolonged seizures or a series of seizures lasting more than 30 minutes) carries a high risk for the mother and fetus. Fortunately, status epilepticus is an uncommon complication of pregnancies.

-- Excerpted from "Women with Epilepsy: A Handbook for Health and Treatment Issues" edited by Martha J. Morrell, MD and Kerry L. Flynn, M.A. Published by Cambridge University Press, 2003. It is available for purchase in our marketplace.