by Alan Mallinger, M. D., Associate Professor Of Psychiatry And Pharmacology, University of Pittsburgh School of Medicine
Because bipolar disorder typically has an early age of onset, it often affects women during their childbearing years. Since all of the currently approved and recognized mood stabilizers used in this condition (lithium, valproate, carbamazepine) pose significant risks to the fetus in terms of birth defects, the woman with bipolar disorder who wants to have a child must choose between discontinuing her medication and placing herself at risk for developing an episode of depression or mania, or placing her unborn child at risk for malformations. All too often, the woman decides to discontinue medication, only to suffer an episode several months later, either before she has become pregnant or at an early stage of pregnancy.
In a 1996 article in a Stanley Center for Innovative Treatment of Bipolar Disorder publication, Dr. K. N. Roy Chengappa discussed risks to the fetus from in utero exposure to lithium. He noted that while the risk of cardiac abnormalities appears to be less than reported in early studies, there remains an increased risk of such abnormalities among babies born to mothers who were exposed to lithium during the first trimester. Other types of birth defects such as spina bifida (a defective closure of the bony encasement of the spinal cord) are also reported to be increased among such babies. Dr. Chengappa concluded that the incidence of major congenital abnormalities among infants born to lithium-exposed mothers was four percent to 12 percent, compared to two percent to four percent for infants of mothers who do not take lithium.
Anticonvulsants have also been implicated in increasing the risk of birth defects. Neural tube defects such as spina bifida as well as other birth defects, have been associated with exposure to valproate and to a lesser extent with carbamazepine. For anticonvulsants in general, the risk of major malformations is four percent to six percent and is probably above this range for valproate. Anticonvulsants may also produce other types of medical complications during pregnancy.
The National Institute of Mental Health has recently begun an initiative to identify safer mood-stabilizing medications for use in pregnancy. The first drug slated for testing is verapamil, a calcium channel blocking agent that has been used in several previous studies on the treatment of manic episodes. Verapamil produces effects that are similar to those of lithium, yet it has an acceptable safety profile in pregnancy. Hopefully, this planned investigation will begin to provide more and better alternatives for women who need ongoing treatment with mood stabilizers during the childbearing years.
--from Innovations, vol. 2, no. 3 (Spring 1997)