Risk for cognitive deficit in a population-based sample of U.S. children with autism spectrum disorders: Variation by perinatal health factors
published online 02 March 2010.
Abstract
Background
From 30% to 60% of children with an autism spectrum disorder (ASD) have an IQ measure that falls in the intellectual disability (ID) range. It is not well studied whether, for children within this ASD subgroup, there is variation in the risk for low IQ based on a child's perinatal risk factors.
Objective/Hypotheses
We assessed whether preterm delivery and term small-for-gestational-age (tSGA) were associated with various measures of cognitive deficit among children with ASDs.
Methods
A sample of 1129 singleton children born in 1994 and identified through school and health record review as having an ASD by age 8 years were selected from a U.S. population-based surveillance network. Mean IQ and dichotomous IQ outcomes indicating various levels of ID were examined according to whether a child was preterm (<37 weeks' gestation) or tSGA (term delivery and birth weight <10th percentile for gestational age of a U.S. referent). Results for the total sample and within race-ethnicity/maternal education strata were adjusted for child sex and ASD subtype classification.
Results
Mean IQ was significantly (p < .05) lower in children delivered preterm (69.5) than term (74.5) and tSGA (69.3) than term appropriate-for gestational age (75.3). In stratified analyses, the preterm-IQ association was significant only among non-Hispanic white (NHW) children with maternal education at birth of high school or less; adjusted mean IQ was 8 points lower among those delivered preterm (65.4) than term (73.8). Term-SGA was associated with a significant 8-point deficit in adjusted mean IQ (75.5 vs. 83.8) in NHW children with maternal education greater than high school and a 6-point deficit that approached significance (68.4 vs. 74.5, p=0.10) in NHW children with maternal education of high school or less. Non-Hispanic black children in both maternal education groups had significantly lower mean IQs than NHW children with little variation by preterm or tSGA.
Conclusions
In children with ASDs, the risk for concurrent ID or IQ deficit is associated with both preterm delivery and tSGA; these associations may vary by race-ethnicity and SES. Further studies of ASD-ID co-occurrence and the effectiveness of intervention strategies should consider both perinatal and sociodemographic factors.
aNational Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA
bWaisman Center, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA
cDept of Community and Family Health, College of Public Health, University of South Florida, Tampa, FL 33612, USA
dDepartment of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
eColorado Department of Public Health and Environment, Denver, CO 80246, USA
fDepartment of Medicine, Division of Biostatistics and Epidemiology, Medical University of South Carolina, Charleston, SC 29425, USA
gUniversity of Arizona College of Medicine, Tucson, AZ 85724, USA
Corresponding author: MS E-86, 1600 Clifton Road. Fax: (404) 498-3550.
Financial disclosure: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease and Control and Prevention. Dr. Rice conducts a limited number of training sessions to professionals on the diagnosis of the autism spectrum disorders as an approved outside activity separate from employment with the federal government. The other authors report no conflicts of interest.
ABSTRACT