We think about medications taken during pregnancy in three general categories:
- Medications known to cause birth defects or other serious problems
- Medications not known to cause birth defects but which we can’t be confident are safe
- Medications we know are safe
Unfortunately, none of the mood stabilizer medications are in that third category. None have been proven to be completely safe or free from risk.
Some of the anticonvulsant-type medications (carbamazepine, oxcarbazepine, valproate, and divalproex) fall into the first category. They can significantly increase the risk of serious birth defects, including spina bifida and other neural tube defects. With these medications, we say this: don’t take them if you are pregnant and don’t get pregnant while you are taking them.
Because lamotrigine is an anticonvulsant, we used to assume that it also increased the risk of the same serious birth defects. However, newer research has not shown that to be the case, so we now put lamotrigine in the middle category. There is no clear risk of birth defects, but we don’t know enough to say that there is no risk. Any woman considering taking lamotrigine during pregnancy must weigh the possible risk against the risk of not taking lamotrigine.
Similarly, lithium was once thought to significantly increase the risk of heart defects. Newer research finds that there is some increase in risk, but it is smaller than previously believed. As a result, lithium now also falls into that middle group: we have to balance possible risks against the risks of stopping lithium. Women who choose to continue lithium during pregnancy should have more frequent lab tests, since the physical changes during pregnancy and delivery can cause big changes in lithium levels.
The second-generation antipsychotic medications (risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole, etc.) also fall into the middle category. There is no proven risk of birth defects, but we don’t have enough experience to say they are completely safe. Since these medications are newer, there has also been less time to learn about possible risks. Therefore, we might be more cautious with newer medications than with some of the older ones.