Background Peripartum anxiety and depressive disorders are associated with adverse consequences for mother and child. Thus, it is important to examine risk factors, correlates and course patterns of anxiety and depressive disorders during pregnancy and after delivery. Methods In the prospective-longitudinal Maternal Anxiety in Relation to Infant Development (MARI) Study, n=306 expectant mothers were recruited from gynaecological outpatient settings in Germany and completed up to seven waves of assessment from early pregnancy until 16 months postpartum. Anxiety and depressive disorders and potential risk factors/correlates were assessed with the Composite International Diagnostic Interview for Women (CIDI-V), medical records and additional questionnaires. Results Although peripartum anxiety and depressive disorders appeared to be persistent in some women, others reported major changes with heterogeneous courses and shifts between diagnoses and contents. There was a considerable amount of incident disorders. Strongest predictors for peripartum anxiety and depressive disorders were anxiety and depressive disorders prior to pregnancy, but psychosocial (e.g. maternal education), individual (e.g. low self-esteem), and interpersonal (e.g. partnership satisfaction, social support) factors were also related. Limitation Knowing the aims of the study, some participants may have been more encouraged to report particular symptoms, but if so, this points to the importance of a comprehensive assessment in perinatal care. Conclusion Peripartum time is a sensitive period for a considerable incidence or persistence/recurrence of anxiety and depressive disorders albeit the course may be rather heterogeneous. Interventional studies are needed to examine whether an alteration of associated factors could help to prevent peripartum anxiety and depressive disorders.