Because the onset of mood and anxiety disorders often occurs during the childbearing years, many women may be taking psychotropic medications for these disorders when they conceive. These medications easily diffuse across the placenta, and their impact on the fetus is of concern. But discontinuation may lead to relapse, in which case psychiatric symptoms may affect the fetus. Thoughtful treatment planning presents a dilemma to the clinician. Limited data suggest heightened vulnerability to relapse of mood and anxiety disorders in women during the postpartum period. Pregnancy appears to exacerbate symptoms of obsessive-compulsive disorder, while panic disorder patients may remain well after discontinuing medication. Future studies should address the prevalence and relapse rates of mood and anxiety disorders, particularly after medication discontinuation, among pregnant women.