Abstract. In the last month of pregnancy and the first weeks of lactation, intensive adaptations processes, both morphological and functional, take place in the cow's body. An organism adapts through changes in the intensity of metabolic processes and the activity of its regulatory mechanisms. Maintaining the homeostasis of an organism in prepartum and postpartum periods is the key condition in health maintaining of the mother and the foetus/calf. This paper presents studies on changes in the levels of progesterone, estrogens, androgens, placental lactogen, relaxin, pregnancy glycoproteins, prostaglandin F2α, cortisol, oxytocin, prolactin, GnRH, LH, FSH, thyroid hormones, insulin and growth hormone, significantly associated with the growth and development of the foetus, preparation of the mammary glands for lactation, and, after parturition, with reproductive system regeneration and preparation for new fertilization and pregnancy.