Maternal illness and autism
© 2012 Roy Benaroch, MD
This week’s autism headline: Flu, fever during pregnancy linked to autism risk.
Researchers in Denmark reviewed health information from a group of about 100,000 children born between 1997 and 2003. The mothers had been interviewed during and shortly after their pregnancies to determine who had had infections, fevers, or other health issues during pregnancy. Now that the children had grown to 8-14 years of age, the study looked backwards to see if the children developed autism had mothers who reported more infections or fevers during pregnancy.
The good news: for many minor infections, including common colds or short-lived fevers, there was no significant association with autism. However, mothers who had recalled having the flu had about double the risk of autism in their children, and mothers who reported a fever lasting over a week had triple the risk.
The authors themselves stress that these are preliminary findings, and that their complicated mathematics could have exaggerated trends that aren’t really significant. Still, there is animal data that shows inflammation from infection during pregnancy can indeed influence fetal brain development. These findings about flu and fever are plausible.
This study adds to the growing evidence that at least in many cases, the causes of autism begin well before a baby is born. Previous research has shown in increased risk of autism with older fathers, maternal obesity, and closely spaced pregnancies. It is very likely that there are numerous, overlapping causes of autism that include genetic, prenatal, and environmental factors. We’re learning more and more, but we’ve still got far to go.
Back to the current study: the overall risk of having a child with autism following influenza is still low—there is no need for panic or extensive watchfulness. However, this study provides yet more evidence that pregnant (or expecting-to-get-pregnant) moms need to protect themselves from infection. Eat right, sleep right, wash your hands, avoid sick people. And please, get yourself and your children influenza vaccines. Want to avoid autism? Vaccinate!