Objectives. To determine if: 1) Month or season of conception is associated with increased risk of autism, 2) Maternal self reported influenza infection or fever during pregnancy is associated with increased risk of autism, 3) High probability of exposure to influenza and influenza like illnesses during pregnancy is associated with autism.
Methods. To reach each objective, we conducted 3 studies corresponding to three chapters. The first and third chapters analyzed birth cohorts of children born in California between January 1990 and December 2002. The birth files of these cohorts were matched to databases of the California Department of Developmental Service (DDS) to identify children who developed autism before their 6th birth day. For the first chapter, the exposure was month or season of conception. For the third chapter, we used county level rates of hospitalization for influenza and influenza like illnesses as a surrogate for maternal exposure to influenza. The second chapter utilized data from a large population based study known as the Childhood Autism Risk from Genetics and Environment (CHARGE). In this study, the exposure was maternal self-reported influenza and fever during pregnancy and was assessed through standardized questionnaires.
Results. Chapter1: Children conceived in December (OR= 1.09, 95% CI 1.02–1.17), January (OR = 1.08, 95% CI 1.00–1.17), February (OR = 1.12, 95% CI 1.04–1.20) or March (OR = 1.16, 95% CI 1.0–1.24) were at higher risk of developing autism compared to those conceived in July. Conception in the winter season was associated with a 6% (OR = 1.06, 95% CI 1.02–1.10) increased risk compared to summer.
Chapter2: We did not find an association between self-reported influenza during pregnancy and autism. However, we found that uncontrolled fever during pregnancy was associated with autism (weighed odd ratio = 2.55 95% CI 1.30–4.99)
Chapter3: High probability of maternal exposure to influenza during pregnancy was associated with autism. (OR= 2.62 95 % CI 2.36–2.90).
Conclusion. Uncontrolled maternal fever during pregnancy was associated with autism. Maternal self-reported influenza was not associated with autism but high probability of exposure to influenza in early pregnancy was associated with autism. The observed association of high probability of exposure to influenza and autism can likely be due to the fever resulting from influenza infection. If our results of the association between fever during pregnancy and autism are confirmed, it could have implications in the prevention of future new cases.
|Commitee:||Iosif, Ana-Maria, Walker, Cheryl K.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 73/07(E), Dissertation Abstracts International|
|Subjects:||Public health, Epidemiology|
|Keywords:||Autism, Fever, Influenza, Prenatal influenza infection, Risk|
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