Postural and motor asymmetries in newlyborns.

Twelve full-term newlyborns were examined during wakefulness for head turning and maintenance of head position within the first hour after birth. Ten showed a rightward bias on both these measures. This is the youngest age since birth at which such lateralized functions have been reported. In all infants head position was strongly related to the hand which contacted the mouth but not with contacts to other parts of the face. The reason for this difference is discussed and it is suggested that head position and hand-mouth contacting may form a lateralized synergism which biases the development of handedness.