THURSDAY, May 12 (HealthDay News) -- Influenza during pregnancy and non-elective cesarean delivery do not appear to be associated with an elevated risk of autism spectrum disorder (ASD); however, fever during pregnancy, especially in the first or second trimester, and factors associated with difficult labor are associated with an increased risk of ASD, according to research presented at the International Meeting for Autism Research, held from May 12 to 14 in San Diego.
Using data from the Childhood Autism Risk from Genetics and Environment (CHARGE) study, Ousseny Zerbo, of the University of California at Davis, and colleagues evaluated 462 children with ASD, 136 with developmental disorders but not autism, and 265 typically developed children between ages 2 and 5 (when recruited) to determine whether maternal influenza infection or fever during pregnancy was associated with an increased risk of ASD. The investigators found no association between maternally reported influenza during pregnancy and ASD. However, mothers of ASD-affected children were twice as likely to report having had a fever during pregnancy as compared with mothers of typically developing children, with the risk especially elevated if the fever was during the first or second trimester.
Also using data from the CHARGE study, Robin L. Hansen, M.D., of the University of California at Davis, and colleagues evaluated medical records documenting the course of labor and delivery for mothers of 477 children with a diagnosis of ASD and 272 population-based frequency-matched controls. The investigators found that non-elective cesarean delivery itself was not associated with ASD but that factors associated with difficult labor courses may raise the risk. Other research revealed that maternal diabetes and other conditions related to elevated insulin resistance may play a role in the development of ASD among offspring, and that elevated tumor necrosis factor levels in amniotic fluid are associated with a significantly increased risk of ASD.
"Our analysis suggests that it is not birth by cesarean itself that is associated with ASD. Rather, it appears that factors associated with difficult labor courses, including prolonged labor and membrane rupture, as well as occult and overt infection within the amniotic cavity may drive the relationship between non-elective cesarean delivery and ASD," Hansen and colleagues write.
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