Premature Births, Pregnancy Complications Associated With Increased Autism Risk for Infants, Study Says

Main Category: Autism
Article Date: 18 May 2005 - 17:00 PST

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Infants who are delivered before 35 weeks gestation or in a breech position, have an Apgar score of seven or lower five minutes after birth or are born to parents with histories of mental illness are more likely than other infants to develop an autism spectrum disorder, according to a study conducted in part by... CDC and published in the May 15 issue of the American Journal of Epidemiology, the Atlanta Journal-Constitution reports. Heidi Larsson and colleagues from the North Atlantic Neuro-Epidemiology Alliances studied 698 children born in Denmark after 1972 and diagnosed with an autism spectrum disorder before 2000 and more than 17,000 nonautistic children born in the country during the same time period. Researchers found:

• Infants born before 35 weeks gestation were about 2.5 times as likely as infants born between 37 and 42 weeks gestation to be diagnosed with an autism spectrum disorder;
  
  
• Infants born in a breech presentation -- buttocks emerging first -- were 1.63 times as likely as infants born head first to have autism;
  
  
• Infants who five minutes after delivery scored seven or lower on the Apgar test -- a composite test measuring heart rate, respiratory effort, muscle tone, skin color and reflex irritability -- were 1.89 times as likely as infants with Apgar scores of 10 at five minutes after birth to develop autism;
  
  
• Children born to parents with no history of psychiatric disorder were 3.41 times less likely to develop autism than children born to parents who have been diagnosed with schizophrenia-like psychosis and 2.91 times less likely to develop autism than infants born to parents who have been diagnosed with depression (Wahlberg, Atlanta Journal-Constitution, 5/17);
  
  
• A "statistically significant" association between high parental age -- a mother older than 30 years or a father older than 35 years -- and autism; and
  
  
• No statistically significant association between autism and multiple gestation, preeclampsia, number of previous pregnancies, number of prenatal visits or smoking reported at first prenatal visit (Larsson et al., American Journal of Epidemiology, 5/15).
  

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Previous research has suggested a link between increased risk of autism and prenatal complications, parental psychiatric history and socio-economic status of the parents, but CDC said the study did not provide a "definitive link" between autism and "troubled births" or other factors, Reuters reports. "At this point, we don't know for sure if these events are causes, but it certainly points us to look more closely at what happens during pregnancy as a possible opportunity for future prevention," Diana Schendel, a CDC epidemiologist and one of the authors, said (Simao, Reuters, 5/16). Jose Cordero, director of CDC's National Center on Birth Defects and Developmental Disabilities, said the study "also indicates there may be some children for whom we need extra vigilance in watching for signs of developmental delay" (CDC release, 5/16). An unnamed spokesperson for the United Kingdom's not-for-profit National Autistic Society said, "Many experts believe that the pattern of behavior from which autism is diagnosed may not result from a single cause" (BBC News, 5/17).

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