Anticonvulsants Cause Birth Defects

by Marcia Purse

Published studies have found that women taking anticonvulsant medications during pregnancy run a substantially higher risk of having a child with birth defects. This is of serious concern to the bipolar community, since some of the epilepsy medications involved in this study are also used as mood stabilizers, and women who take any of these drugs for migraine headaches should also be aware of the findings.

Researchers screened over 100,000 expectant mothers at five Boston area hospitals between 1986 and 1993 and identified those who had ever had a seizure. After certain factors had been taken into consideration (such as multiple births), they found:

• Group 1: 223 women who had taken one anticonvulsant during pregnancy;
• Group 2: 93 who had taken two or more anticonvulsants during pregnancy; and
• Group 3: 98 who had taken anticonvulsants before, but not during, pregnancy.

In addition, they selected a control group of 508 infants whose mothers stated they had had seizures but had never taken anticonvulsant medications. After the children were born, they were examined carefully for major birth defects such as:

• small head or body size;
• malformations that would have medical, surgical or cosmetic importance (including spina bifida, cleft palate, cardiovascular defects and others); and
• hypoplasia of the mid-face (flattened face) and fingers (inadequate development). See right hand hypoplasia. WARNING: You may find this image disturbing.
  NOTE: Finger defects were rare in the group taking anticonvulsants that are also mood stabilizers.

The doctors who examined the infants for defects did not previously know, in 93 percent of cases, which group each infant belonged to.

The results were sobering. In Group 1, 20.6 percent of infants had major birth defects. In Group 3, the figure rose to 28 percent. In both the control group and Group 3, where mothers had stopped taking anticonvulsants before becoming pregnant, the percentage was 8.5 percent.

Excite News quoted Dr. Martha Morrell, chief of the epilepsy center at Columbia University's medical school, as saying, "I don't think this paper allows us to say that the epilepsy doesn't enter into it at all," adding that the women who were not taking medication probably did not have epilepsy as severe as the other mothers did." However, 35 women in the study were taking one of the drugs as a mood stabilizer or for control of migraine or pain (although they also reported seizures), and in this smaller group, too, the prevalence of major birth defects was similar to that in the overall medicated group.

Among the women who had taken one anticonvulsant drug, 87 had taken phenytoin (Dilantin), 64 phenobarbital, 58 carbamazepine (Tegretol), 6 valproic acid (Depakote, Depakene), 6 clonazepam (Klonopin), 1 diazepam (Valium), and 1 lorazepam (Ativan). The first two are not used as mood stabilizers. The study found that spina bifida, a serious condition where the back of the spine is left open, endangering the spinal cord, was the most common birth defect found when mothers had taken both carbamazepine and valproic acid (either together or switching from one to the other during pregnancy), two drugs frequently used as mood stabilizers. Carbamazepine alone was found to cause serious defects as well. (The four drugs listed that only a few women were taking appear to have been taken only in combination with one of the first three listed.)

The researchers noted that some severe defects were detected during pregnancies which were then terminated, and these incidents were not able to be included in the study due to lack of controls. Also, changing medications during the pregnancy produced the same increased percentage of defects as did taking two medications at once.

Faced with these figures, we are convinced that these medications, especially Tegretol (carbamazepine), present a substantial danger to the child if taken during pregnancy. A woman should discuss the risks with her psychiatrist before becoming pregnant in order to make an informed decision. Women taking carbamazepine or valproic acid (Depakote, etc.) who are pregnant should tell the obstetrician and psychiatrist and make sure the development of the fetus is monitored closely.

Reference

Holmes, L.B., Harvey, E.A., Coull, B.A., Huntington, K.B., Khoshbin, S., Hayes, A.M. & Ryan, L.M. (2001, April 12). The teratogenicity of anticonvulsant drugs. New England Journal of Medicine.