Women with epilepsy have a 90% chance of having a healthy, normal baby. The chance that children of parents with epilepsy will also develop the disorder depends on the type of epilepsy the parents have and whether it is a hereditary form of the disorder. There are two main factors in the cause of epilepsy. One is whether the person has had an injury to the brain, such as from an accident or an infection. The other factor is the seizure threshold.
The seizure threshold is a person's level of resistance to seizures. Everyone has a seizure threshold, and anyone can have a seizure under certain conditions. People with a low seizure threshold may suddenly start having seizures. People with a high threshold are less likely to start having seizures unless something specific happens, such as an injury to the brain.
The seizure threshold is part of the genetic makeup that is passed on from parent to child. There may be several people with epilepsy in some families; in others, there may be only one. The chance of a child's developing epilepsy depends on the seizure threshold of both parents (if they have epilepsy).
Sometimes epilepsy is part of an inherited medical condition. This is rare, but includes neurofibromatosis and tuberous sclerosis. Neurofibro-matosis is a familial condition producing multiple soft tumors that may appear in the nervous system, muscles, bone, and skin along with pig-mented areas. Tuberous sclerosis is a rare genetic multisystem disorder that is typically obvious shortly after birth. The disorder may be characterized by episodes of uncontrolled electrical activity in the brain (seizures); mental retardation; distinctive skin abnormalities (lesions); and benign (noncan-cerous), tumorlike nodules (hamartomas) of the brain, certain regions of the eyes (retinas), the heart, the kidneys, the lungs, or other tissues or organs.
Genes play a part in the development of epilepsy, but their importance varies. Every situation is different, and women with epilepsy are advised to consult a geneticist (a doctor who specializes in genetics). The geneticist can help determine the chances of the baby's developing a specific type of epilepsy. Tests performed by the doctor (amniocentesis and ultrasound) can help determine that the baby is developing normally.
Because AEDs can slightly increase the risk for birth defects, most doctors ask women with epilepsy to tell them at least 3 months in advance if they plan to conceive so their AEDs can be adjusted, if necessary, and folic acid and multivitamins can be prescribed. If you become pregnant before consulting your doctor, however, you should continue taking your medications as prescribed. Once you tell your doctor you are pregnant, the doctor will probably prescribe blood tests. The test results, the medications you are taking, and the number of seizures you may be having will help determine the amount of medication you should take on a daily basis.
Each year about 20,000 women with epilepsy become pregnant. Over the years, that number has increased because of increased marriage rates, and because society has accepted the fact that men and women with epilepsy can be great parents and do just as well as anyone else. During that time, the epilepsy community has made tremendous progress through research for pregnant women. New tests and procedures have made it possible to watch the development of the fetus and detect any abnormalities before birth.
During your pregnancy, the number of seizures you have may change. For pregnant women with preexisting epilepsy, approximately 35% experience more frequent seizures, 55% have no change in the frequency of seizures, and approximately 10% have fewer seizures during pregnancy.
The reasons women may experience changes in the number of seizures include:
❖ Changes in sex hormones
❖ Changes in AED metabolism, volume, or distribution
❖ Changes in renal clearance (the rate at which the kidneys are able to clear the plasma of a substance) or protein binding
❖ Changes in sleep schedules
❖ Irregularity in taking medication
The concentration of AEDs may change during pregnancy. A number of physiologic changes during pregnancy can alter the effect of AEDs, including the following:
❖ Changes in stomach and intestinal absorption of AEDs
❖ Decreased gastric tone (which determines the sensitivity of the stomach to distention)
❖ Motility (the movement of foods in the gastrointestinal system)
❖ Increase in renal clearance
Albumin, a major protein in plasma, is a volume expander. As it expands, it helps to keep the blood from leaking out of the blood vessels. Fluid may collect in the ankles, lungs, or abdomen when albumin levels drop. Albumin is vital for tissue development and healing. It is also needed for protein binding, as the carrier proteins that carry substances around the blood, including antiepileptic drugs.
One part of antiepileptic drugs—the biologically active part—occurs free (unbound) in the blood. Because there is an increase in the free part of AEDs when both albumin levels and protein binding decline, it is necessary to follow the nonprotein-bound drug concentration (the free level) of AEDS, especially for AEDS that are highly protein-bound, such as carbamazepine, phenytoin, and valproic acid. The unbound or free portion of antiepileptic drugs in some cases may provide more accurate clinical information to your physician.
Controlling seizures during pregnancy is extremely important, because women with epilepsy are at greater risk for miscarriage. The reasons for miscarriage are not completely understood, but they are probably related more to maternal seizures than to the fetus's being exposed to AEDs. This is supported by the finding of fetal heart rate decelerations during maternal seizures.
The older medications that control seizures, such as the benzodiaze-pines, phenytoin, carbamazepine, phenobarbital, and valproic acid, are teratogenic, meaning they can cause birth defects if a woman gets pregnant while she is taking them. Minor malformations present at birth, including facial dysmorphism (abnormal shape of the face) and digital anomalies (minor abnormalities in the developmental and shape of the fingers), occur in 6% to 20% of infants exposed to AEDs in utero. This is approximately a twofold increase over the general population. These defects are typically slight and are often outgrown. The most common birth defects are cleft lip and palate. Cleft palate is a non-life-threatening birth defect in which there is a split in the roof of the mouth.
Cardiac defects and urogenital defects (structural abnormalities of the kidney and sexual organ system) occur in 4% to 6% of babies born to mothers with epilepsy who are taking the older types of AEDs (such as phenobarbital), compared with 2% to 4% of the general population. Neural tube defects such as spinal bifida and anencephaly (absence of the brain and spinal cord) occur in 0.5% to 1% of infants exposed to carbamazepine, and 1% to 2% of infants exposed to valproic acid during the first trimester. The risk of birth defects is highest in fetuses exposed to multiple medications and in those exposed to higher dosages. A study confirmed these observations, finding an increased number of major birth defects, growth retardation, microcephaly (abnormal smallness of the head), and hypopla-sia (incomplete development) of the midface or fingers in children born to mothers taking two or more of the older AEDs.
Since 1993, a number of new medications for epilepsy have been available for usage. The U.S. National Pregnancy Registry has little information regarding the teratogenicity of the newer medications for epilepsy. All of these are listed by the Food and Drug Administration as Use-in-Pregnancy Risk Category C medications—meaning the risks are not known and therefore cannot be ruled out. Registries have been established to gather data about fetal outcome after exposure to the newer AEDs.
In the United States, the Antiepileptic Drug Registry can be reached by telephone (1-888-233-2334) or at the registry's Web site (www.aed pregnancyregistry.org). Pregnant women with epilepsy can enroll in this registry if they want to participate in studies. Participation in these studies will help doctors understand epilepsy and pregnancy and enable them to find new ways to help women with epilepsy. The main goal of the studies is to help future mothers have a safe pregnancy with as few seizures as possible.
Although the data are limited, there are increasing concerns that exposure to AEDs in utero may have long-lasting, unfavorable neurodevel-opmental or neurocognitive effects. A retrospective study found that children exposed in utero to valproic acid in monotherapy (single-drug therapy) or polytherapy (multiple-drug therapy) were more likely to require special educational resources. Prospective studies are underway to describe better the neurodevelopmental risks to the developing brain from exposure to AEDs.
Folic acid deficiency is a possible cause of teratogenicity for phenytoin, carbamazepine, phenobarbital, and valproic acid. Unfortunately, there are no definitive studies on the effect of folic acid supplementation in women with epilepsy, and several studies report inconsistent results. For example, one study associated lower serum levels of folic acid with a higher risk of defects in children of mothers taking folic acid during their pregnancy. Another reported a decrease in children who were born with major malformations when their mothers took folic acid during pregnancy. Still others reported no decrease in the risk of non-neural-tube defects, such as cleft lip and palate and cardiovascular and urinary tract malformations for the babies born of mothers who took folic acid during pregnancy. There was a report of one baby who was born with a neural tube defect to a mother who took 2,000 mg of valproic acid per day and folic acid.
Although there has been insufficient research, many medical societies, including the American Academy of Neurology, the American College of Obstetric and Gynecologic Physicians, and the Canadian Society of Medical Geneticists, suggest that all women of childbearing age who take medicine to control seizures should also take folic acid at 0.4-5.0 mg per day. The U.S. Centers for Disease Control also recommends that all women of childbearing age receive routine supplementation of folic acid of at least 0.4 mg per day.
The most popular way to control seizures during pregnancy is monotherapy at the lowest effective dosage, whenever possible. The best AED to take while you are pregnant is the one that controls your seizures and is well tolerated. At the time of this writing, there is not enough information to distinguish any particular seizure medication that is the safest during pregnancy. It would be wonderful to have just one medication that could control all seizures for every person who has epilepsy. Unfortunately, this is not likely to happen soon. Until then, pregnant women with epilepsy should work with their neurologists to find the best alternatives.
Pregnant women with epilepsy will need to see a neurologist or epilep-tologist and obstetrician more often than pregnant women who do not have epilepsy. These health care professionals monitor pregnancy closely in order to ensure the best outcome for mothers and their babies.
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Prior to planning pregnancy, you should learn more about the things involved in getting pregnant. It involves carrying a baby inside you for nine months, caring for a child for a number of years, and many more. Consider these things, so that you can properly assess if you are ready for pregnancy. Get all these very important tips about pregnancy that you need to know.