Prenatal maternal infection and risk for autism in offspring: A meta-analysis.
Treating maternal infection during pregnancy may slightly cut autism risk, but the effect is modest and not a stand-alone prevention plan.
01Research in Context
What this study did
Tioleco et al. (2021) pooled 36 studies on moms who had infections while pregnant. They asked: do these babies later get autism more often?
The team looked at any infection, fever, or bad flu during pregnancy. Over 2 million births were in the mix.
What they found
Kids whose moms had an infection during pregnancy had a slightly higher chance of autism. The rise was small: about 1 extra case in every 100 births.
The link showed up across many countries, but the size stayed modest every time.
How this fits with other research
Syriopoulou-Delli et al. (2012) saw no autism jump after moms smoked while pregnant once family income and schooling were counted. This seems opposite, but the two risks are different: infection sparks immune signals, while smoke does not. The papers do not clash; they just test unlike exposures.
Zhao et al. (2024) adds that moms with unplanned pregnancies who skipped folic acid had almost triple the autism odds. Both studies point to early pregnancy hardship, and both hint that quick, low-cost care—treating fever or giving vitamins—may help a little.
Duker et al. (1991) first noted small birth issues in high-functioning autism. Nina’s bigger 2021 review widens the lens to all autism levels and sharpens the focus on infection timing.
Why it matters
You cannot change genes, but you can act on infections. Tell pregnant clients to treat fevers fast and keep prenatal checkups. The benefit is small, yet it is immediate and costs almost nothing. Note this in parent training and early-intervention intakes so medical and ABA teams stay on the same page.
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02At a glance
03Original abstract
While prenatal maternal infection has received attention as a preventable and treatable risk factor for autism, findings have been inconsistent. This paper presents the results of a meta-analysis to determine whether the weight of the evidence supports such an association. Studies with a categorical diagnosis of autism as the outcome and an assessment of its association with prenatal maternal infection or fever (or the data necessary to compute this association) were included. A total of 36 studies met these criteria. Two independent reviewers extracted data on study design, methods of assessment, type of infectious agent, site of infection, trimester of exposure, definition of autism, and effect size. Analyses demonstrated a statistically significant association of maternal infection/fever with autism in offspring (OR = 1.32; 95% CI = 1.20-1.46). Adjustment for evident publication bias slightly weakened this association. There was little variation in effect sizes across agent or site of infection. Small differences across trimester of exposure were not statistically significant. There was some evidence that recall bias associated with status on the outcome variable leads to differential misclassification of exposure status. Nonetheless, the overall association is only modestly reduced when studies potentially contaminated by such bias are removed. Although causality has not been firmly established, these findings suggest maternal infection during pregnancy confers an increase in risk for autism in offspring. Given the prevalence of this risk factor, it is possible that the incidence of autism would be reduced by 12%-17% if maternal infections could be prevented or safely treated in a timely manner. LAY SUMMARY: This study is a meta-analysis of the association of maternal infection during pregnancy and subsequent autism in offspring. In combining the results from 36 studies of this association we find that a significant relationship is present. The association does not vary much across the types of infections or when they occur during pregnancy. We conclude that the incidence of autism could be substantially reduced if maternal infections could be prevented or safely treated in a timely manner.
Autism research : official journal of the International Society for Autism Research, 2021 · doi:10.1002/aur.2499