The prevalence and origins of left hand preference in high risk infants, and its implications for intellectual, motor and behavioural performance at four and six years

This study investigates the origins of hand preference at 4 years in a cohort of 115 high risk and premature infants; it investigates the relationship between their hand preference and intellect development, motor development, temperament and behaviour at 4 and 6 years. Increased left hand preference was independently associated with extreme prematurity, high neonatal risk, increased numbers of minor physical anomalies, lowered intellect and motor abilities and more difficult temperament. Support for pathological mechanisms producing left handedness was found predominantly in the infants of high birth weight, whereas prevalence of left handedness was increased mainly among the extremely low birth weight infants. In the latter group infants with normal intellect were also found to be left handed, suggesting mechanisms other than brain damage being important.