[The problem of the relations between month of birth and psychic disorders (author's transl)].

Groups of 730 each Schizophrenics, Affectpsychotics, and Psychopaths of approximately the same age are compared with 3.650 controls according to their month-of-birth-frequency distribution. (Also included in the comparison are Schizophrenics, Manic-depressifs, Psychopaths, Hysterics as well as the siblings of the Manic-depressifs and Psychopaths of the study by Lang, 1931.) Schizophrenics show significant deviations in the total yearly distribution of birth as well as in 2 or 3 consecutive months - increased birth-frequency in November, December, January, decreased birth-frequency in February, March and in August, September. In the case of the Affectpsychotics only significant decreased birth-frequency can be detected for March. The month-of-birth-frequency distribution for Psychopaths is for the most part identical with that of the control group. The results are compared with the existing studies in this field of research, and possible biological explanations are discussed. Further research is necessary to identify the pathogenetic factors.