A difficult birth or a history of mental illness in a parent may put a baby at greater risk for autism. The Centers for Disease Control and Prevention presented a study of 698 Danish children with the developmental disorder and the researchers found a disproportionately high number had been born before the 35th week of pregnancy, had suffered from low birth weights and were in a breech position at birth. The children, all of whom were born after 1972 and diagnosed with autism before 2000, also were more likely to have a parent who had been diagnosed with schizophrenia-like psychosis before the autism was discovered. Previous research had suggested that perinatal factors, parental psychiatric history and socioeconomic status might represent or include risk factors for autism. The CDC, however, noted that the latest findings did not indicate a definitive link between autism and troubled births or other possible risk factors. Autism permanently impairs development of those areas of the brain that control verbal and nonverbal communication as well as social interaction. About one out of every 250 babies in the nation (US) are born with the disability, which usually appears in the first three years of childhood, according to the Autism Society of America. Some parents have claimed that their children developed autism due to exposure to childhood vaccines containing the preservative thimerosal, an organic compound that is 49 percent mercury. Thimerosal was used routinely in the United States between the 1930s and the 1990s to prevent bacterial and fungal contamination of a wide range of infant vaccines, including those for hepatitis B. Thimerosal is no longer used in childhood vaccines in the United States, but remains in the influenza vaccine and in vaccines in other countries. The CDC, which launched a campaign earlier this year to make doctors and parents more aware of the need for early diagnosis of autism and other developmental disorders, said it had found no proof of a link between autism and vaccines.
American Journal of Epidemiology,
May 2005