Prenatal exposure to fever is associated with autism spectrum disorder in the boston birth cohort.

Autism spectrum disorder (ASD) is phenotypically and etiologically heterogeneous, with evidence for genetic and environmental contributions to disease risk. Research has focused on the prenatal period as a time where environmental exposures are likely to influence risk for ASD. Epidemiological studies have shown significant associations between prenatal exposure to maternal immune activation (MIA), caused by infections and fever, and ASD. However, due to differences in study design and exposure measurements no consistent patterns have emerged revealing specific times or type of MIA exposure that are most important to ASD risk. No prior studies have examined prenatal MIA exposure and ASD risk in an under-represented minority population of African ancestry. To overcome these limitations, we estimated the association between prenatal exposure to fever and maternal infections and ASD in a prospective birth cohort of an understudied minority population in a city in the United States. No association was found between prenatal exposure to genitourinary infections or flu and the risk of ASD in a nested sample of 116 ASD cases and 988 typically developing controls in crude or adjusted analyses. Prenatal exposure to fever was associated with increased ASD risk (aOR 2.02 [1.04-3.92]) after adjustment for educational attainment, marital status, race, child sex, maternal age, birth year, gestational age, and maternal smoking. This effect may be specific to fever during the third trimester (aOR 2.70 [1.00-7.29]). Our findings provide a focus for future research efforts and ASD prevention strategies across diverse populations. Autism Res 2017, 10: 1878-1890.