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26th Feb 2017

Fever and flu in pregnancy can increase autism risk, study finds

Trine Jensen-Burke

Around the world, doctors and scientist are hard at work trying to solve the medical riddle that is autism.

Now, it seems, a study in Denmark seems to have, if not solved it, then at least added another piece to the puzzle by discovering that women who had the flu while they were pregnant were more than twice as likely to have a child later diagnosed with autism.

Even more importantly; those who had a fever lasting a week or longer, whether caused by the flu or something else, were a whopping three times as likely to have an autistic child.

This study, conducted at the University of Aarhus in Denmark, came about after several other studies had pointed to inflammation being a possible link when it came to autism – and a total of 96,000 children in Denmark took part.

A team including Dr. Hjördis Ósk Atladóttir of the University of Aarhus in Denmark, Diana Schendel of the U.S. Centers for Disease Control and Prevention – and their respective colleagues – studied a big database of children born in Denmark between the years of 1997 and 2003 and their mothers.

To conduct their research, Atladóttir and Schendel interviewed the women twice while they were pregnant and then again when their babies were six months old – specifically about sicknesses they had, and about the drugs they took to treat them.

Out of the children involved, 976 of them were later diagnosed with an autism spectrum disorder – a number which makes up about one percent.

And what the study, published in the journal Pediatrics, found, was that mothers who said they had influenza (the flu) while pregnant were more likely to have children later diagnosed with autism.

“We found almost a twofold increased risk of infantile autism in the child after self-reported infection with influenza virus during pregnancy,” the researchers wrote. “Children whose mothers said they had a fever lasting more than a week during pregnancy had triple the risk of autism.”

Interestingly, women who reported other infections, such as a cold, a urinary tract infection or herpes, were not more likely to have a child with autism.

To the medical community, the Danish study raised as many questions as it did answers – but did fit in with a growing body of evidence that suggests that, in at least some cases, something is going on with a mother’s immune system during pregnancy that affects the developing child’s brain.

But it is important to stress, adds Dr. Coleen Boyle, Director of the US National Center on Birth Defects and Developmental Disabilities to NBC News, that this does not mean that the infection caused autism and women should not panic if they become ill while pregnant.

“We want to reassure women. In this study, most women who experienced flu or prolonged fever or who were taking antibiotics did not have children with an autism spectrum disorder.”

Many studies in this area have been and are currently being conducted, often with inconclusive or opposite results, making it all the harder for researchers to be able to fully understand the connection between inflammation and autism.

A Swedish study from a while back found no association between flu or any other infection and autism, while a US study at the University of California-Davis MIND Institute did, showing that women who had fevers while pregnant were twice as likely to have a child with autism or a developmental disorder.

It is also important to note that the researchers are keen to stress that the misreporting of what is or isn’t influenza is likely to be considerable and that any episode of fever can indeed be mistaken for the flu.

“More research is needed,” concludes both Atladóttir in Denmark and Boyle in the US.