Maternal hospitalization with infection during pregnancy and risk of autism spectrum disorders

Animal models indicate that maternal infection during pregnancy can
result in behavioral abnormalities and neuropathologies in offspring. We
examined the association between maternal inpatient diagnosis with
infection during pregnancy and risk of ASD in a Swedish nationwide
register-based birth cohort born 1984-2007 with follow-up through 2011.
In total, the sample consisted of 2,371,403 persons with 24,414 ASD
cases. Infection during pregnancy was defined from ICD codes. In the
sample, 903 mothers of ASD cases (3.7%) had an inpatient diagnosis of
infection during pregnancy. Logistic regression models adjusted for a
number of covariates yielded odds ratios indicating approximately a 30%
increase in ASD risk associated with any inpatient diagnosis of
infection. Timing of infection did not appear to influence risk in the
total Swedish population, since elevated risk of ASD was associated with
infection in all trimesters. In a subsample analysis, infections were
associated with greater risk of ASD with intellectual disability than
for ASD without intellectual disability. The present study adds to the
growing body of evidence, encompassing both animal and human studies,
that supports possible immune-mediated mechanisms underlying the
etiology of ASD.