Influence of Physical Characteristics on Temperature Profile in Normal Neonates at an Early Neonatal Stage

To understand temperature profiles and to identify factors affecting these profiles in the early neonatal stage, body temperature was monitored using a deep thermometer in 10 normal neonates placed in a room at 26–27°C from 2 h 31 min to 7 h after birth. Temperature data were used to investigate correlations between physical characteristics measurements, body-mass indices, gestational weeks and time of birth. No significant differences were observed in chest deep temperature values between any measurement time points. The degree of decrease in chest deep temperature was significantly larger in Group AL (mean value of individual subject is lower than total mean value) than in Group AH (mean value of individual subject is higher than total mean value) up to 5 h after birth. Degree of decrease in chest deep temperature tended to be larger in Group RH (rectal temperature immediately after birth of individual subject ≥37.0°C) than in Group RL (rectal temperature immediately after birth of individual subject <37.0°C) up to 4.5 h after birth.Regarding physical characteristics, head circumference was significantly larger in Groups AH and RL and body-mass indices of head circumference/body mass and chest circumference/body mass were generally larger in Groups AL and RH. Body surface area did not differ significantly between any groups, but body surface area/body mass ratio was significantly larger in Group AL than in Group AH. Body temperature changes were shown to fluctuate in the lower range in neonates with larger head circumference/body mass ratio and chest circumference/body mass ratio and body surface area/body mass ratio at an early neonatal stage after birth.