Neonatal thermoregulation.

The human being is a homeotherm. Homeothermy is a result of thermoregulation which includes many physiological processes. Thermoregulation maintains an equilibrium between heat production (thermogenesis) and heat loss (thermolysis). There are three principal modes of heat production: 1. Voluntary muscle activity. 2. Involuntary tonic or rhythmic muscle activity known as "shivering". 3. Non-shivering thermogenesis (NST) essential for newborns. Heat loss occurs in two stages: 1. The flow of heat from the center of the body to its surface. 2. The flow of heat from the body surface to the environment by conduction, convection, radiation or water evaporation. Even in the very small premature baby, we find that metabolic and vasomotor control responses are developed. To protect the newborn from stress resulting from hypo or hyperthermia, one should take into consideration the concept of the neutral temperature range which is also called the "Thermoneutral Zone" in (TNZ) or "Thermal Neutrality". Curves, proposed in 1971 by Hey are essential for keeping newborns in the TNZ.