Carbamazepine is a drug often prescribed to treat epilepsy and bipolar disorder. Some doctors offer it to pregnant patients who suffer from these conditions, but there are several risks that come with this drug. This is why the U.S. Food and Drug Administration (FDA) ranks carbamazepine as a Pregnancy Category D drug that presents a risk to the fetus. The risk of birth defects, ranging from facial deformities to spina bifida, is increased when women take carbamazepine in pregnancy. The only time this medication should be used by pregnant women is when its benefits are thought to outweigh the risks.
Studies in both humans and animals show the use of carbamazepine in pregnancy tends to increase the risks of certain birth defects. This may include heart problems and deformities of the head or face and, while some problems may be considered minor, others are life-threatening. There also is a risk of spina bifida, which is a neural tube defect that keeps the spinal cord from closing properly while the fetus is inside the womb. This risk is especially high in mothers who take carbamazepine during the first four to six weeks of their pregnancy, which is when the developing backbone is supposed to begin covering the spinal cord. For this reason, some doctors only prescribe carbamazepine after this period of the pregnancy, because this may at least lessen the risk of spina bifida occurring as a result of using this drug.
Some babies do not develop any birth defects because of carbamazepine in pregnancy, but they may still be affected once they are born. For example, they may have trouble breathing on their own right after birth, and they may have seizures. Diarrhea and vomiting also are side effects displayed by some newborns whose mothers took this drug. While these symptoms may not sound serious or long-term, they can be quite dangerous for newborn babies unless they are treated quickly.
Despite the risks of taking carbamazepine in pregnancy, some doctors still prescribe this medication to treat epilepsy. This is likely because epilepsy tends to become worse during pregnancy as a result of hormonal changes, and having several seizures while pregnant also can harm the baby. To combat some of the risks associated with taking carbamazepine in pregnancy, doctors may advise women to start taking folic acid supplements to help prevent spina bifida from occurring, because this condition tends to appear most in women with low levels of this substance. In addition, studies have shown that taking more than one medication to prevent seizures can increase the chances of birth defects, so many doctors make sure their patients only take a single drug during pregnancy. While carbamazepine is often taken by pregnant women to control epilepsy, few women need to take it to treat bipolar disorder while pregnant because there are less dangerous drugs available for this use.