Is infant holding-side bias related to motor asymmetries in mother and child?

Studies have revealed a preference for the left hemibody in infant holding in 65-85% of cases. Several investigations have linked this preference to maternal asymmetries. The main goal of the present study was to assess manual and hemispheric asymmetries in both mother and child and delineate their respective influence on holding-side biases. Holding side was assessed by direct observation, and by use of a questionnaire within populations of mother-child dyads. Maternal asymmetries were handedness and hemispheric specialization for perceiving emotions. Infant asymmetries were fetal position, asymmetric tonic neck reflex (ATNR) at birth and handedness at 19 months of age. To that purpose a longitudinal study has been made with infants observed at 2 and 19 months of age. A significant relationship was found between maternal handedness and holding preferences, but no significant relation was obtained between hemispheric specialization and holding preferences. Fetal position in utero but not ATNR, was significantly related to holding-side preferences. Finally, holding side at 2 months was significantly associated with infants' unimanual preferences.