Fatally organized alimentary system hydrolase activities in a newborn make up the initial digestive polyenzyme potential, which provides breast milk lacto trophy if combined with hydrolases. Initial digestive potential in a newborn is characterized by the results of the activity and content of lipase, α- amylase, pepsinogens (I, II), alkaline phosphatase, α1-antitrypsin in umbilical cord blood serum, amniotic fluid, aspirate gastric content in a newborn at the end of the delivery. Systems of different hydrolases during antenatal life are asynchronous. According to the results of the hydrolase estimation in the blood serum of the mother and the newborn, the digestive potential of the latter turns out to be much less than that of the mother’s. It is the proof of the incomplete maturity of the digestive potential in the newborn. In the case of immature gestation, the concentration of hydrolases and zymogens (except lipase) in the examined bio liquids was reduced. Hydrolases of gastric contents are most informative towards the digestive potential and less informative towards amniotic fluids and umbilical cord blood serum.