Incubation of very immature infants.

The range of thermal control and the thermoneutral range of preterm infants under 30 weeks' gestation was calculated by extrapolation of data from studies on more mature infants. Even assuming some thermoregulatory capacity, the range of control is less than 3 degrees C, the thermoneutral range is less than 0.5 degrees C, and both are greatly influenced by the rate of transepidermal water loss. Measurements of metabolic rate and effective thermal environment made on 6 infants under 30 weeks' gestation in the first week of life showed that the very preterm infant exerts little thermoregulatory control and that variations in transepidermal water loss are a major factor determining the appropriate thermal environment.