The puerperium is a period of increased psychic vulnerability and postpartum depression (PPD) is the most common obstetric complication. In the last classification of the American Psychiatric Association (DSM-5) (2013), the specifier “with postpartum onset” was replaced by the specificer “with peripartum onset” to acknowledge the fact that many PPDs start during pregnancy. However, the postpartum denomination remains a valid one and should be kept regardless the depression started in pregnancy or up to six months postpartum. Puerperal depressive symptoms may be found in the postpartum blues, unipolar or bipolar PPD or puerperal affective psychosis. PPD and psychosis cause impairment of maternal functioning and affect the mother-infant relationship. Timely treatment and prevention of these disorders minimize risks and favour the health of the mother and that of the offspring.