Behavioral and adrenocortical responses to stress in neonates and the stabilizing effects of maternal heartbeat on them

Adrenocortical response to stress in neonates was assessed by estimating salivary concentrations of cortisol, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEA-S). Behavioral responses to stress were also scored clinically, according to the method of Lewis and Thomas [15]. The modulation of these measures by hearing maternal heartbeat was also evaluated. Levels of cortisol and DHEA in saliva in neonates correlated well with those of serum showing significant variation in painful stress. Hearing the maternal heartbeat significantly reduced the grade of variation, but the recorded sound of the Japanese drum with the same rhythm showed no significant effect. Scores of the behavioral response to stress also decreased significantly in neonates who were presented with the maternal heartbeat in comparison with those hearing no sound or the beat of a Japanese drum.