The dynamics of the index of stress in ontogeny

Mathematical analysis of the heart rate in foetuses reveals the progressive development of regulatory mechanisms which account for fetal maturity. The decrease in sympathetic tonic mechanisms, the onset and development of normo- and vagotonic mechanisms of regulation of chronotropic function of the heart were revealed in postnatal ontogenesis. Phasic structure of regulatory processes during the increase in loading was observed in the organism of children, infants and young subjects.