Epilepsy is the most common neurologic condition in women of reproductive age, and approximately 1 percent of pregnancies occur in women who have seizure disorders. Controlling epilepsy during pregnancy is of utmost importance, as seizures can place pregnant women and their developing babies at risk for permanent injury or even death. However, even though most infants born to women with epilepsy are normal, many of the medications used to control seizures are known to cause birth defects. Lamotrigine (Lamictal), a medication used to treat epilepsy and bipolar disorder, appears to be safer than many other antiepileptic drugs, but its use should be closely monitored during pregnancy.
1. Fetal Risk Unclear
According to a 2007 review in “Canadian Family Physician,” most studies have not shown an increased risk for major birth defects in infants of mothers who take lamotrigine during pregnancy. However, the North American Antiepileptic Drug Pregnancy Registry, which assesses the impacts of antiepileptic drug exposures during the first trimester, revealed a higher incidence of cleft lips or cleft palates in infants whose mothers took lamotrigine. Five of 564 infants in this registry were born with cleft lips or palates. Among the infants who were not exposed to lamotrigine, the incidence of cleft lip or palate was around 4 in 10,000.
2. Pregnancy Decreases Levels
The blood level of any antiepileptic drug must be maintained at a concentration high enough to prevent seizures, but low enough to not cause serious side effects. Therefore, “therapeutic ranges” have been established for many antiepileptic drugs, and their dosages are typically adjusted to keep patients’ levels within the therapeutic range. In lamotrigine’s case, no universally accepted therapeutic range has been established. Rather, lamotrigine’s dosage is gradually increased until your seizures are controlled. To further complicate dosing issues, your body metabolizes and eliminates lamotrigine more rapidly during pregnancy, which could lead to “breakthrough” seizures or increased bipolar symptoms in women whose conditions were well controlled prior to pregnancy. To prevent such problems, your doctor may measure your lamotrigine level from time to time and increase your dosage if your blood level falls.
3. Adverse Reactions
The most common side effects associated with lamotrigine include nausea, dizziness, blurred or double vision and loss of coordination. These side effects are more common when you first start taking lamotrigine or if your dosage is too high. Rare but potentially serious reactions to lamotrigine include rashes, bone marrow suppression and severe hypersensitivity reactions that can cause multi-organ failure. While adverse reactions to lamotrigine are not necessarily more common during pregnancy, they may be confused with pregnancy-related disorders such as morning sickness, anemia or preeclampsia. Therefore, any rashes, unusual fatigue or other worrisome symptoms should be promptly reported to your physician.
Pregnant women who suffer from seizure disorders or bipolar disorder may not have the option to discontinue their medications. While lamotrigine appears to be safer during pregnancy than many other antiepileptic drugs, at least one study has linked it to an increased risk for birth defects. In contrast, the International Lamotrigine Pregnancy Registry, an 18-year compilation of data from nearly 1,600 pregnancies, showed that major birth defects were no more common among infants of mothers using lamotrigine than they were in the general population. Your doctor will help you decide whether lamotrigine is appropriate for you, and you may be advised to participate in a registry that monitors antiepileptic drug use during pregnancy.
- Canadian Family Physician: Teratogenicity of Lamotrigine
- Journal of Research in Medical Sciences: Epilepsy Drugs and Effects on Fetal Development: Potential Mechanisms
- GlaxoSmithKline: Lamictal Prescribing Information
- Neurology: Lamotrigine in Pregnancy
- Neurology: Final Results From 18 Years of the International Lamotrigine Pregnancy Registry (abstract)
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