Relation between intrauterine growth and subsequent intellectual disability in a ten-year population cohort of children in Western Australia

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). The odds of ID increased with less-than-optimal intrauterine growth. In Caucasian children, after adjustment for sociodemographic factors, severe growth restriction was associated with development of mild-moderate ID among preterm births (< 37 weeks) (odds ratio (OR) = 1.71, 95% confidence interval (CI): 1.06, 2.77) and term births (>= 37 weeks) (OR = 2.42, 95% CI: 1.88, 3.12) and with severe ID (OR = 4.79, 95% CI: 2.59, 8.83) among term births. Effects were similar among Aboriginal children. Severe growth restriction (OR = 3.2, 95% CI: 1.3, 7.9) and poor head growth (OR = 3.6, 95% CI: 1.4, 9.0) were independently associated with severe ID. Infants with excess intrauterine growth were more likely to be diagnosed with ID associated with autism spectrum disorder (OR = 2.36, 95% CI: 0.93, 6.03). These findings suggest that inappropriate intrauterine growth, less than or greater than optimal birth weight, is associated with development of ID.