Mothers who had fevers during their pregnancies were more than twice as likely to have a child with autism or developmental delay, say researchers from the University of California - Davis.
Appearing in the Journal of Autism and Developmental Disorders, the study is thought to be the first to look at how fever from any cause, including flu, and its treatment during pregnancy could affect the likelihood of having a child with autism or developmental delay.
The results showed that flu during pregnancy was not associated with greater risks of having a child with autism or developmental delay. Fever from any cause during pregnancy, however, was far more likely to be reported by mothers of children with autism (2.12 times higher odds) or developmental delay (2.5 times higher odds), as compared with mothers of children who were developing typically. For children of mothers who took anti-fever medication, the risk of autism was not different from the risk in children whose mothers reported no fever.
The study explains that fever is produced by acute inflammation - the short-term, natural immune system reaction to infection or injury - and that chronic inflammation, which no longer serves a beneficial purpose and can damage healthy tissue, may be present in mothers with metabolic abnormalities like diabetes and obesity.
"When people are infected by bacteria or viruses, the body reacts by mounting a healing response that involves the release of pro-inflammatory cytokines from white blood cells into the bloodstream. Some cytokines are able to cross the placenta, and therefore could reach the fetal central nervous system, potentially altering levels of neurotransmitters and brain development," the researchers note.
"Our study provides strong evidence that controlling fevers while pregnant may be effective in modifying the risk of having a child with autism or developmental delay," said Ousseny Zerbo, lead author of the study. "We recommend that pregnant women who develop fever take anti-pyretic medications and seek medical attention if their fever persists."
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Source: University of California - Davis Health System