HONOLULU – Children born at less than 26 weeks' gestation are significantly more likely to have symptoms indicative of autism spectrum disorders at school age than are their classmates, according to a study of 219 children born extremely preterm matched with 153 children born at term.
Samantha Johnson, Ph.D., who is a psychologist at the University of Nottingham (England), and her colleagues compared these extremely preterm children with term classmates matched for age, sex, and ethnic group.
The mean age of children in both groups was 11 years, the researchers wrote in a poster presentation at the annual meeting of the Pediatric Academic Societies.
Parents completed the Social Communication Questionnaire (SCQ), which evaluates autism spectrum symptoms, and psychologists administered the Kaufman Assessment Battery for Children (K-ABC), an IQ test.
Compared with the control group, the extremely preterm children had significantly higher total scores on the SCQ as well as significantly higher scores on each of the three component scales: social interaction, communication, and repetitive behavior. These significant differences persisted even after adjustments for both IQ and sex.
A total score of 15 or above on the SCQ is often used to define a threshold for autism spectrum disorders, and a score of 22 or above is used to define a threshold for autism. Of the preterm children, 8% had SCQ scores between 15 and 21, and another 8% had scores of 22 or above.
In contrast, only 3% of their term classmates passed the threshold for autism spectrum disorders, and none passed the threshold for autism. Compared with their classmates, the extremely preterm children were 6.3 times more likely to have scores of 15 or above.
In an interview, coinvestigator Dr. Neil Marlow, professor of neonatal medicine at the University of Nottingham, emphasized that it would not be appropriate to interpret the results as indicating that extreme prematurity is associated with a formal diagnosis of autism. The results show an association between prematurity and autism spectrum disorder symptoms, not autism itself.
Although other studies have found associations between prematurity and autism spectrum disorder symptoms at the age of 2 years, the investigators stated that this is the first study to find that association among school-age children. The investigators reported that they had no relevant conflicts of interest.