Prenatal exposure to fever is associated with autism spectrum disorder in the boston birth cohort.
Martha Brucato, Christine Ladd-Acosta, Mengying Li and 6 others
PMID 28799289WHAT IT FOUND
Mothers who reported fever during pregnancy had children more likely to have ASD after accounting for other factors.
The link was not seen before accounting, or when similar mothers were compared. Flu and genital or urinary infections were not linked.
Key findings
01After adjustment, maternal fever during pregnancy was associated with ASD (adjusted odds ratio 2.02 [1.04-3.92], meaning the modelled odds were 2.02 times the odds in the unexposed group), and third-trimester fever was also associated (adjusted odds ratio 2.70 [1.00-7.29]).
02Adjusted analyses found no association for prenatal flu (adjusted odds ratio 1.17 [0.67-2.05]), genital or urinary infection (adjusted odds ratio 0.69 [0.42-1.14]), or intrapartum fever (adjusted odds ratio 0.60 [0.18-2.02]).
03The fever association was not significant in unadjusted analysis (odds ratio 1.80 [0.99-3.27]) or in propensity score matching.
STILL TO COME
How it was doneWhat they found
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What it does not show
The study did not adjust for multiple comparisons, and the authors state the fever association would not survive a conservative Bonferroni correction. The sample was small, with wide confidence intervals, and the cohort oversampled preterm birth, so the estimates are imprecise and may not represent other populations. Prenatal exposure was self-reported shortly after birth, so fever and infection reporting could be inaccurate; sensitivity analyses could not fully resolve this. ASD was identified from ICD-9-CM codes rather than direct developmental assessment. The fever association was significant only after adjustment; it was not significant in unadjusted analysis or propensity score matching.
Declared interests
The authors state that none of them had any financial conflict of interest pertaining to this work.
The easy way to misread this
Do not conclude that fever causes ASD or that treating fever prevents ASD. This is an observational association, and the fever link was not significant in the unadjusted analysis or in propensity score matching.