New evidence shows that thimerosal, a mercury-based preservative in many vaccines, doesn't increase children's autism development risk, according to a study from the Centers for Disease Control and Prevention (CDC) and reported by Reuters Health.

For the study, the CDC examined data about U.S. children participating in managed care and born between 1994 and 1999. Researchers gathered 256 children with autism spectrum disorder and 752 same-age, same-sex children who didn't have the condition.

When scientists compared the kids, they discovered that children exposed to thimerosal showed no increased risk of developing any type of autism spectrum disorder, no matter when exposure to the preservative occurred.

In fact, children exposed to the preservative between birth and 20 months old had slightly lower odds of developing autism.

“This study should reassure parents about following the recommended immunization schedule,” said Frank Destefano, MD, director of the Immunization Safety Office at the Centers for Disease Control and Prevention in Atlanta, and the study's senior author.

British physician Andrew Wakefield first linked vaccines to autism development more than a decade ago. Although researchers later refuted his claims, by then the damage was done. Panicked parents avoided having their children vaccinated against common childhood diseases, such as measles, mumps and rubella (German measles).

Today, childhood vaccines no long contain thimerosal (it remains in flu shots, though), but autism rates have increased.

What are parents to do?

RH suggests they click here to learn how vaccinations may benefit their child and then decide.