Assessment of adrenocortical activity in term newborn infants using salivary cortisol determinations

Salivary cortisol concentrations were collected every 2 hours over a 24-hour period in eight healthy 2-day-old term neonates. Two maxima in cortisol output were noted, neither being related to the time of day or time since birth. Salivary cortisol concentrations ranged from 2.5 to 57.4 nmol/L (0.09 to 2.08 micrograms/dL), and throughout the 24 hours showed considerable variation (21% to 42%) not related to the state of arousal. The validity of the method was confirmed by collecting matched plasma and saliva samples from another group of 36 neonates. The correlation between plasma and saliva cortisol was r = 0.83. We suggest that salivary cortisol is a useful, noninvasive method of studying adrenocortical status in the newborn infant.