In modern descriptive classification systems all references to aetiology have been elim-inated. Although this approach has advantages in international communication about psychiatric disorders it also pauperized diagnostic thinking, especially in relation to psychiatric disorders associated with childbirth. To date however, the aetiological association between childbirth and the onset of severe depression or psychosis is a well established scientific fact. In this article an overview is given of our present-day knowledge about aetiology, classification, treatment, outcome and prevention.