Brief report: the Brazelton Neonatal Behavioral Assessment Scale detects differences among newborn infants of optimal health.

Objective: To determine whether the Brazelton Neonatal Behavioral Assessment Scale (NBAS) can detect behavioral differences in newborn infants of optimal health and, if such differences appear, also detect gender differences among those neonates.

Methods: Participants were a group of healthy Swedish neonates, 20 boys and 18 girls. The infants were assessed by the NBAS under standardized conditions at 48-72 hours of age, at the midpoint between two meals.

Results: All items except those in the dimensions Autonomic System and Motor System had a wide interquartile range. The trend was that girls had higher median item profiles, which means a higher level of functioning than boys. Four out of seven median values in the dimension Social Interactive Organization, as well as the median value in the self-quieting item in the dimension State Regulation, were significantly higher for girls. The interquartile range of the items seemed wider for boys than for girls.

Conclusions: The results indicate behavioral variability among healthy neonates. Gender differences were also observed with girls showing higher levels of functioning than boys.