Navigating Tx of bipolar disorder in pregnancy.(Obstetrics)

BOSTON -- Managing bipolar disorder during pregnancy requires balancing the competing risks and benefits to the woman and her fetus, said Adele Viguera, M.D.

"Pregnancy, and particularly the postpartum period, is associated with a high risk of disease recurrence for women with bipolar disorder," said Dr. Viguera, director of the perinatal and reproductive psychiatry program at Massachusetts General Hospital in Boston. Although mood-stabilizing drugs can reduce this risk, most are associated with some degree of teratogenicity, she said.

Limited data exist to support the use in pregnancy of the mood stabilizers most commonly used to treat bipolar disorder.

In addition, mood stabilizers have been shown to increase the risk of certain types of birth defects or congenital malformations in infants who were exposed in utero, Dr. Viguera said during a meeting on bipolar disorder sponsored by Harvard Medical School.

To minimize the possibility of fetal damage, some women choose to discontinue their mood-stabilizing regimen, which itself markedly increases the risk of disease recurrence during pregnancy as well as postpartum illness. "More than half of women who discontinue treatment before or during pregnancy relapse, most frequently in the first trimester," Dr. Viguera said.

The risks associated with treatment and treatment cessation vary considerably, depending on the nature and degree of illness and the agents used to treat it. "There is no single optimal management approach," Dr. Viguera said. "Clinical management requires ongoing assessment of maternal and fetal status, risks, and benefits."

Further complicating management is the fact that the Food and Drug Administration has not approved for use during pregnancy any of the psychotropic medications used to treat bipolar disease, because these agents diffuse across the placenta. The risk of birth defects depends on the drug used, when exposure occurs, and the duration of the exposure. It is generally understood that the highest risk to the fetus is during the first trimester, "but later exposure can also lead to malformations, behavioral effects, low birth weight, and preterm delivery," Dr. Viguera said.