Behavioral organization in newborns and its relation to adrenocortical and cardiac activity.

The aim of this study was to assess relations between behavioral organization and adrenocortical and cardiac activity in newborns. Twice during the neonatal period, the behavioral organization of 42 newborns, in terms of orientation and irritability, was assessed by the Neonatal Behavioral Assessment Scale (NBAS), and the newborns' cortisol response to the NBAS procedure was determined. In addition, cardiac activity was assessed during 1 of the NBAS. Whereas there were only inconsistent correlations between newborn irritability and the adrenocortical response during NBAS, low orientation was associated with a higher increase in cortisol in both of the assessments. In addition, orientation was predicted by basal cortisol level. High heart rates were associated with high irritability and low regulation of state, and, in addition, negative relations were indicated between orientation and heart rate variability. The findings support a coping model of biobehavioral relations in newborns.