Psychological disorders always have an impact not only on the individual, but also on all family members, especially partners and children. In the case of a pregnancy, the situation becomes even more complex, as the psychological problem and its treatment might in addition have an impact on the unborn child. Furthermore, psychological problems may compromise fertility and the course of pregnancy, as well as the peri- and postnatal period, and they might be aggravated due to pregnancy and the challenges of motherhood. Pregnancy implies emotional, physical and social changes for the mother, her partner and the rest of the family, but while many mothers greatly enjoy these changes and adapt well to them, others – and especially women at risk for or with pre-existing psychological disorders –may react with severe distress. Women´s socio-economic and cultural context features are modulators of the adaptive responses to the pregnancy, and unfavourable economic conditions or specific social circumstances make it harder to cope. In order to prevent negative long-term effects on the newborn, the mother and the entire family, early detection and adequate care of all pregnant women at risk for psychological maladjustment is of utmost importance and has an impact on mental health and well-being. This chapter describes psychological disorders pregnant women may suffer from, discusses diagnostic procedures as well as treatment options and explains preventive strategies.