Postpartum depression affects 10-15 % women after childbirth. There is no currently generally accepted theory about the causes and mechanisms of postpartum mental disorders. The principal hypothesis concerns the association with sudden changes in the production of hormones affecting the nervous system of the mother and, on the other hand, with the ability of receptor systems to adapt to these changes. We observed changes in steroidogenesis in the period ar ound spontaneous delivery. We collected three samples of maternal blood. The first sampling was 4 weeks prior to term; the second sampling was after the onset of uterine contractions (the beginning of spontaneous labour); the third sampling was during the third stage of labour (immediately after childbirth). Additionally, we collected mixed umbilical cord blood. The almost complete steroid metabolome was analyzed by gas chroma tography-mass spectrometry followed by RIA for some steroids. Mental changes in women in the peripartum period were observed using the Hamilton Depression Rating Scale. The local Ethics Committee approved the study. We found already th e changes in androgens levels correlating with postpartum mood disorders four weeks prior to childbirth. The strongest correlations between steroid and postpartum mood change were found in venous blood samples collected from mothers after childbirth and from umbilical cord blood. The main role played testosterone, possibly of maternal origin, and estrogens originating from the fetal compartment. These results suggest that change s in both maternal and fetal steroidogenesis are involved in the development of mental changes in the postpartum period. Descriptions of changes in steroidogenesis in relation to po stpartum depression could help clarify the causes of this disease, and changes in some steroid hormones are a promising marker of mental changes in the postpartum period., A. Pařízek, M. Mikešová, R: Jirák, M. Hill, M. Koucký, A. Pašková, M. Velíková, K. Adamcová, M. Šrámková, H. Jandíková, M. Dušková, L. Stárka., and Obsahuje bibliografii