Mood disorders are common in women. A prepregnancy personal history of mood disorder (bipolar or major depression), premenstrual syndrome, or (possibly) postpartum blues places a woman at high risk for a postpartum exacerbation of symptoms. Untreated or unrecognized postpartum mood disorders can lead to serious psychologic and social consequences, in some cases even leading to suicide or infanticide. Women at risk for postpartum mood disorders need to be referred for psychiatric consultation before pregnancy and parturition. Informed, professional collaboration offers the best opportunities for prevention, as well as the earliest recognition and treatment of emergent symptoms.