This review focuses on the interrelationships between common psychiatric illnesses and the course of pregnancy, postpartum, and breastfeeding. Within the life cycle context, the impact of childbearing on existing disorders or vulnerabilities in the female patient is of primary interest, as well as episodes that are etiologically related to childbearing. Treatment considerations for psychiatric disorders during childbearing invoke special modifications of the risk-benefit decision-making process. Mental health is fundamental to health. For the pregnant woman, the capacity to function optimally, enjoy relationships, manage the pregnancy, and prepare for the infant’s birth is critical. Perinatal health can be conceptualized within a model that integrates the complex social, psychological, behavioral, environmental, and biologic forces that shape pregnancy. Unipolar and bipolar mood disorders, which are common in pregnant and postpartum women, deserve the attention of obstetric providers. Procedures to identify those at risk should begin in pregnancy if not in the preconceptional period.