Psychiatric disorders associated with childbearing are traditionally divided into three categories that reflect severity: postpartum blues, postpartum depression, and postpartum psychosis. It is estimated that while more than 80 percent of women may experience some fluctuations in mood in either the antepartum period or postpartum, only 10 to 20 percent may meet DSM-IV criteria for major depression and 0.1 to 0.2 percent will show signs of psychosis. Pregnancy and childbirth have an enormous combined psychological and physiological effect on a woman's body; a causal link between hormonal changes and changes in mood has been suggested. The evidence (or lack of) for a biological component of postpartum mood disorders is briefly reviewed. Assessment and treatment of antepartum and postpartum mood fluctuations is further discussed with emphasis on more education, recognition, and if possible, prevention of these disorders.