it is not possible to diagnose some variety of affective disorder or schizophrenia. The American Psychiatric Association's Diagnostic and Statistical Manual, whose 5th edition was published in May 2013, allows the use of a 'peripartum onset specifier' in episodes of mania, hypomania or major depression if the symptoms occur during pregnancy or the first four weeks of the puerperium. The failure to recognize postpartum psychosis, and its complexity, is unhelpful to clinicians, epidemiologists, and other researchers. Onset groups Postpartum bipolar disease belongs to the bipolar spectrum, whose disorders exist in two contrasting forms – mania and depression. They are highly heritable, and affected individuals (less than 1% of the population) have a lifelong tendency (diathesis) to develop psychotic episodes in certain circumstances. The 'triggers' include a number of pharmaceutical agents, surgical operations, adrenal corticosteroids, seasonal changes, menstruation and childbearing. Research into puerperal mania is, therefore, not the study of a 'disease-in-its-own right', but an investigation into the childbearing triggers of bipolar disorder. Psychoses triggered in the first two weeks after the birth – between the first postpartum day (or even during parturition until about the 15th day – complicate approximately 1/1,000 pregnancies. The impression is sometimes given that this is the only trigger associated with childbearing. But there is evidence of four other triggers – late postpartum, prepartum, post-abortion and weaning. Marcé, widely considered an authority on puerperal psychoses, claimed that they could be divided into early and late forms; the late form begins about six weeks after childbirth, associated with the return of the menses. His view is supported by the large number of cases in the literature with onset 4–13 weeks after the birth, mothers with serial 4-13 week onsets and some survey evidence. The evidence for a trigger acting in pregnancy is also based on the large number of reported cases, and particularly on the frequency of mothers experiencing two or more prepartum episodes. There is evidence, especially from surveys, of bipolar episodes triggered by abortion (miscarriage or termination). The evidence for a weaning trigger rests on 32 cases in the literature, of which 14 were recurrent. The relative frequency of these five triggers is given by the number of cases in the literature – just over half early postpartum onset, 20% each late postpartum and prepartum onset, and the rest post-abortion and weaning onset. In addition, episodes starting after childbirth may be triggered by adrenal corticosteroids,