In 1797, Osiander, an obstetrician from Tübingen, reported two cases at length – masterly descriptions which are among the treasures of medical literature. In 1819, Esquirol  conducted a survey of cases admitted to the Salpêtrière, and pioneered long-term studies. From that time, puerperal psychosis became widely known to the medical profession. In the next 200 years over 2,500 theses, articles and books were published. Among the outstanding contributions were Delays unique investigation using serial curettage  and Kendells record-linkage study comparing 8 trimesters before and 8 trimesters after the birth. In the last few years, two monographs reviewed over 2,400 works, with more than 4,000 cases of childbearing psychoses from the literature and a personal series of more than 320 cases. Research directions
The lack of a formal diagnosis in the DSM and ICD has hindered research. Research is needed to improve the care and treatment of affected mothers, but it is of paramount importance to investigate the causes, because this can lead to long term control and elimination of the disease. The opportunities come under the heading of clinical observation, the study of the acute episode, long-term studies, epidemiology, genetics and neuroscience. In a disorder with a strong genetic element and links to the reproductive process, costly imaging, molecular-genetic and neuroendocrinological investigations will be decisive. These depend on expert laboratory methods. It is important that the clinical study is also state-of-the-art– that scientists understand the complexity of these psychoses, and the need for multiple and reliable information sources to establish the diagnosis.
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.