Link Between Preterm Birth And Autism Explored, Not Conclusive
There is growing evidence supported by recent studies that suggest that autism spectrum disorder (ASD) may be more prevalent among children born very prematurely. These studies have only opened the door of awareness and in and of themselves are not conclusive. More research needs to be done before absolute conclusions can be drawn.
Preterm birth infants also have an increase incidence of cerebral palsy, vision or hearing problems. These associated issues can make it difficult for doctors to correctly screen children for autism spectrum disorder. This has led researchers to begin to explore the relationship between preterm birth, cognitive and developmental impairments, and ASD.
Dr. Karl Kuban and colleagues from Boston University, Wake Forest University, and Harvard University studied 988 children born between 2002 and 2004 who participated in the ELGAN (Extremely Low Gestational Age Newborn) study. ELGAN is a large, multi-center study that enrolled more than 1500 infants born at least three months prematurely.
Dr Kuban and his colleagues wanted to explore whether children born preterm are more likely to screen positive on the Modified Checklist for Autism in Toddlers (M-CHAT) which is a survey administered to a caregiver regarding a child's behavior. Pediatricians typically wait to formally diagnose autism spectrum disorder until after a child's third birthday. This study administered the M-CHAT when the children were only 24 months of age. The researchers found that 21% of the preterm children screened positive for ASD.
The researchers were also interested in learning whether a child born prematurely who had motor, visual, hearing, or cognitive impairments was more likely to screen positive on the M-CHAT. Of the 988 children, 26% had cognitive impairments, 11% had cerebral palsy, 3% had visual impairments, and 2% had hearing impairments.
It was observed that nearly half of the children with cerebral palsy and more than two-thirds of the children with visual or hearing impairments screened positive for ASD using the M-CHAT. This apparent increase in ASD in these children who screened positive for ASD dropped to 10% when the variables of cognitive, visual, hearing, and motor impairments were removed.
It should be stressed, as it is in the related editorial, by Dr. Neil Marlow and Dr. Samantha Johnson of University College London that because early identification leads to early treatment of children with autism spectrum disorder, screening tests are designed to over-identify children at risk. They suggest that more useful knowledge may be gained by following the children as they mature to determine how many of those who initially screened positive actually develop ASD.
Dr. Marlow notes that the study is valuable because "it raises our awareness of the difficulties in interpreting screening results." He cautions that further research is needed before conclusions can be drawn about the direct correlation between preterm birth and autism spectrum disorder.
"Positive Screening on the Modified Checklist for Autism in Toddlers (M-CHAT) in Extremely Low Gestational Age Newborns" by Karl C. K. Kuban, MD, SM, Epi, T. Michael O'Shea, MD, MPH, Elizabeth N. Alfred, MS, Helen Tager-Flusberg, PhD, Donald J. Goldstein, PhD, Alan Leviton, M, DOI: 10.1016/j.jpeds.2008.10.011.
The accompanying editorial is "Positive Screening Results on the Modified Checklist for Autism in Toddlers: Implications for Very Preterm Populations" by Neil Marlow, MD, and Samantha Johnson, PhD, DOI: 10.1016/j.jpeds.2008.11.028.
The articles appear in The Journal of Pediatrics, published by Elsevier.