Low Birth Weight May Increase Autism Risk

June 3, 2008

The prevalence of autism is higher among low birth weight or preterm children, particularly in females and in children with other developmental disabilities, according to research published in the June issue of Pediatrics.

TUESDAY, June 3 (HealthDay News) -- The prevalence of autism is higher among low birth weight or preterm children, particularly in females and in children with other developmental disabilities, according to research published in the June issue of Pediatrics.

Diana Schendel, Ph.D., and a colleague at the National Center on Birth Defects and Developmental Disabilities at the U.S. Centers for Disease Control and Prevention in Atlanta, conducted a two-part retrospective cohort study of 434,091 surviving children born in Atlanta between 1981 and 1993, and sorted out those with developmental disabilities as defined by the Metropolitan Atlanta Developmental Disabilities Surveillance Program. In the second step, they took a nested case-controlled sample from the cohort of 617 children identified as having autism and a control group of subjects who were not identified as having developmental disabilities.

The investigators found that birth at fewer than 33 weeks' gestation and birth weight under 2500 g were associated with roughly twice the risk of developing autism, although the risk varied according to gender and autism subgroup (higher among girls and for those with autism accompanied by other developmental disabilities). Girls with a low birth weight were four times as likely to have autism accompanied by mental retardation, although boys with a low birth weight were not at greater risk for autism alone, the report indicates.

"Gender and autism subgroup differences in birth weight and gestational age, resulting in lower gender ratios with declining birth weight or gestational age across all autism subgroups, might be markers for etiologic heterogenicity in autism," the authors conclude.

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