M ood changes have been documented during and following pregnancy. The two most frequently reported mood changes that accompany pregnancy are changes in levels of anxiety and depression. Generally, there is an increase in anxiety reported dur1 ing pregnancy. There may be symptoms of anxiety mixed with depression in 2 3 many women, and Hayworth, Little, Carter et al reported that high anxiety is associated with postpartum depression. This situation is further complicated by the fact that commonly employed pharmacological interventions used to treat psychological disturbances are often contraindicated during and following pregnancy. Thus, it is important that the efficacy of nonpharmacological interventions, such as exercise, be explored. The prescription of exercise in the treatment of emotional disorders has gained popularity in recent years. It has been reported that 85% of primary care physicians, for example, prescribe exercise in the treatment of depression, and 60% prescribe exercise in the management of anxiety. There have been numerous reviews of literature since 1980 that have concluded that exercise is associated with reduced anxiety and depression. 4--s Also, a general consensus reached by a panel of experts convened by the National Institute of Mental Health was that exercise is associated with reductions in mild to moderate levels of anxiety and depression. However, the majority of research has been conducted primarily with male subjects and nonpregnant women. In a preliminary pilot study, changes in state anxiety were assessed in ten pregnant women before and following an exercise session. There were questions concerning the intensity of exercise and whether it would be sufficient to produce psychological changes. Results from this pilot investigation revealed moderate aerobic exercise was associated with a significant reduction in state anxiety in a small sample of pregnant women. In the present investigation, anxiety and depression levels of pregnant women who participated in an exercise session were compared with pregnant women who participated in a nonexercise session. The nonexercise session consisted of a prenatal childbirth information session offered through a local hospital. It was © 1994 by The Jacobs Institute of Women's Health 1049-3867/94/$7.00