Pregnancy, Fever, and Autism

I've Got a Fever... [Day 080/365]
Creative Commons License photo credit: rocknroll_guitar

One of the most frustrating things about Autism, of course, is that we really don’t know what causes it. Researchers have identified certain risk factors, and many other potential causes have been identified (and left wanting for scientific evidence).

According to one new study involving fever during pregnancy suggests that women who had a fever while pregnant had twice the risk of their baby having autism.

The findings mesh with other research linking diabetes and obesity during pregnancy to a higher risk of having a child with a developmental delay or autism. The two conditions – fever and diabetes – are associated with an inflammatory response in the body that researchers say may injure the developing brain.

Researchers from the UC Davis MIND Institute, which is dedicated to studying autism, say the latest findings build on discoveries about risks and protections faced by pregnant women in Northern California. Risks for having a child with autism also include living within a quarter-mile of a highway. Protections include taking prenatal vitamins before and during pregnancy.

“We’re adding more pieces to the set of evidence to try to figure it all out,” said Irva Hertz-Picciotto, a professor of public health at UC Davis and principal investigator of CHARGE, the Childhood Autism Risks from Genetics and the Environment study.

Hertz-Picciotto said the findings were based on questionnaires filled out by more than 1,100 mothers of typically developing children and those with children with developmental delays or autism.

The study did not show an elevated risk of having a child with autism if mothers had the flu. But a fever from any cause, such as a bacterial infection, during pregnancy was twice as likely to be described by mothers with children with autism and 2.5 times more likely in mothers of children with developmental delays.

Mothers who took anti-fever medication had the same risk of having a child with autism as mothers who reported no fever, the study found.

The fever study raises the question of whether chemicals the body releases to fight infection, called cytokines, may pass through the placenta and have a damaging effect on the fetus, said Ousseny Zerbo, lead author of the study, who was a doctoral candidate with UC Davis when the study was conducted.

Zerbo said cytokines are produced during acute inflammation that occurs when someone has a fever. The chemicals are also produced steadily in people with diabetes, who have a 2.3 times higher risk of having a child with developmental delays.

The findings are similar in magnitude to a phase of the CHARGE study that examined women who lived near a highway when pregnant. The study found that women who reported living within 1,000 feet of a major freeway during the third trimester of pregnancy were 2.2 times more likely to have a child with autism.

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