A Danish study published online today in Pediatrics is already causing concern among pregnant women — and sparking criticism.
After NBC aired a segment about the study on "Today," questions about the methods used in the study arose as quickly as alarming headlines suggesting a link between fever or flu during pregnancy and autism.
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The Danish researchers questioned mothers of almost 100,000 children born in Denmark between 1997 and 2003 about their history of infection, influenza and antibiotic use during pregnancy.
The results initially seem significant:
Women who reported having the flu while pregnant were twice as likely to have kids who developed autism.
A week-long fever indicated a tripled risk. But, as the authors themselves point out, "misreporting of influenza is likely to be considerable," and "The results may be due to multiple testing; the few positive findings are potential chance findings."
Others questioned the comparisons drawn in the study: "The more comparisons you make, the more likely some difference will look important when it's not," Emily Willingham wrote for Forbes.
" study is purely explorative and it is far too soon to suggest any clinical implications," HealthDay quotes study lead author Dr. Hjordis Osk Atladottir, of the Institute of Epidemiology and Social Medicine at University of Aarhus.
"Indeed, the study shows that around 99 percent of women experiencing influenza, fever or taking antibiotics during pregnancy do not have children with autism."
Other recent studies have had mixed findings: a Swedish study found no link between infections and autism, although a study from the U.S. found that women who had fevers while pregnant were twice as likely to have a child with autism or a developmental disorder, and another Danish study showed an association between hospital visits in the first trimester and autism.
While the results of the study may be speculative, advice seems to be consistent on one front: if you're pregnant, get a flu shot.