Leonard H et al. - The authors investigated the association between intrauterine growth and intellectual disability (ID). The appropriateness of intrauterine growth was assessed using percentage of optimal birth weight, a measure that accounts for gestational age, maternal height, parity, and infant sex. Using population-based record linkage, singleton Caucasian and Aboriginal children born in Western Australia in 1983–1992 and alive in 2002 with ID of unknown cause (n = 2,625) were compared with children without ID (n = 217,252)