Behavioral gender differences in the neonatal period according to the Brazelton scale.

The aim of the present study was to analyze gender differences in neonatal behavior. A sample of 188 healthy full-term newborns (88 boys and 100 girls) was assessed. The behavioral evaluations were performed using the Brazelton Neonatal Behavioral Assessment Scale (NBAS), when the infants were between 48 and 80 hours old. Girls had higher scores than boys in 4 out of the 34 behavioral items of the NBAS. These are the following: Orientation Animate Auditory (t=2.486; P=0.014), Alertness (t=2.546; P=0.012), Quality of Alertness (t=3.091; P=0.002), and State Regulation (t=2,343; P=0.020). Boys had higher scores in the Irritability item (t=-2.186; P=0.030). We have analyzed also the possible effects of the medication during delivery because mothers of boys were more likely to have used this medication but no differences have been found among the mentioned items. These results appear to confirm that similarities between boys and girls are much more the norm than differences related to gender, but even though they are quite subtle, differences do exist in the way newborn infants react and behave in the neonatal period.