The most frequently occurring pre- and postpartum psychiatric disorders are depression and, to a lesser degree, panic disorder and psychosis. Apart from the negative effects on the psychological well-being of the mother, these psychiatric disorders may also result in obstetric complications and an impaired mother-infant relationship. In order to prevent these negative effects, mothers who are at risk for major psychiatric disorders need to be identified early, preferably before or during pregnancy. The most important risk factor is a history of psychiatric disorders. Obstetric risk factors for depression are unplanned or unwanted pregnancy, pregnancy-related hypertension, emergency caesarean section and early discharge from the hospital. Other factors are low socioeconomic status, recent life event, negative self-image, little social support, immigration in the last 5 years, feelings of loss of control during pregnancy and feeding problems with the child. For treatment, pregnant or puerperal women with a possible psychiatric disorder based on the presence of a serious risk factor, such as a previously experienced psychiatric disorder (related to pregnancy or not), serious current psychiatric symptoms or long-time use of psychoactive drugs, should be referred preferably to a combined psychiatric/obstetric clinic or, if unavailable, to a psychiatrist in a general hospital.