New research out of Denmark seems to show a higher risk of autism in babies born to women who had the flu while pregnant, and in those babies born to women who had a fever for longer than a week during pregnancy. In the study, women who had a normal pregnancy had an autism risk of about 1%.  The study, published in Pediatrics online November 12, 2012, was done as a combination of telephone interviews and gathering diagnoses of autism from the Danish Psychiatric Central Register. Women were not tested to see if they actually had the flu, but the study results do give some reason for caution. The study included over 96,000 children born in Denmark between 1997 and 2003. While most common infections during pregnancy did not seem to have any effect on the child, mom getting the flu during pregnancy seemed to double the risk of autism, and mom having a prolonged fever (about a week or longer) seemed to triple the risk of autism.

The good news is that even the highest risk group in the study, that with fever during pregnancy lasting a week or more, still only had an autism rate of 3%. The other piece of good news is that women are able to take actions to reduce their risk of becoming ill during pregnancy.

Many experts recommend that all pregnant women get a flu shot to help reduce the risk of getting influenza. Since flu shots are most effective against the strains of flu in the shot that year, and there are many different strains of flu, some women are concerned about how effective the shot really is. There are also some concerns about the safety of the shot, including the use of thimerosal (a mercury-based preservative) in some batches of flu vaccine. While the CDC states that the small amounts of thimerosal in flu vaccines have not been shown to cause harm, some people are still concerned because of how small the developing baby is. Studies have shown that Thimerosal accumulates in brain tissue and can contribute to neurological problems. Thimerosal has been removed from all vaccines given to children in the United States because of these concerns of possible mercury toxicity. Fortunately for those who want to get a flu shot, there are shots available without mercury.

There are also many other things a woman can do to support her immune system and reduce the likelihood of getting sick during pregnancy, or to get better more quickly if she does get sick. These are great to use in case the shot does not cover all of the common strains of flu out this year, or for those women who prefer to avoid the flu shot.