An average of one in 110 children - roughly one percent of 8-year-olds - have autism, according to data collected in multiple communities nationwide from 2006.
Overall, the data indicates that one in 70 boys and one in 315 girls have an Autism Spectrum Disorders (ASD), the Centers for Disease Control and Prevention reported Friday.
ASD refers to a group of symptoms including a profound inability to communicate, mental retardation, and other developmental disorders - from mild to severe, reports CBS News medical correspondent Dr. Jennifer Ashton. The diagnosis can be complicated and subjective.
"It's not like going out and measuring a blood test. This isn't concrete like that, this is looking at behavior," said Dr. Gary Goldstein of the Kennedy Krieger Institute.
The new research reveals an overall increase in autism from earlier studies. According to the newest data, all 10 communities participating in an earlier 2002 study observed autism prevalence shoot up by an average of 57 percent.
Arizona and Missouri saw the highest uptick in autism prevalence while Florida had the lowest rate, according to the research.
The ASD prevalence was 4 to 5 times higher for boys than for girls.
The study used data based on a retrospective review of health and education records from communities compromising eight percent of the U.S. population of eight-year-olds. The studies focused on eight-years-old because previous research has shown that most children with autism have been identified by this age.
The studies' authors noted that it was impossible to pinpoint one reason for the increase in autism.
"Although some of the increases are due to better detection, a true increase in risk cannot be ruled out," the researchers noted.
In analyzing the numbers, Ashton reports, researchers are wrestling with an important issue: Are there really more autistic children? Or does the growing awareness of the symptoms lead to more diagnoses?
"Based on everything we have right now, I would say it's more likely than not that there is an increase in the number of cases. It's not absolute," Dr. Goldstein said.
Jennifer Chancellor has been a special education teacher for 14 years; she told Ashton that she's seen a big change in perceptions of children's behavior.
"I think there is an awareness of what developmental milestones should be hit for children, and I think when there is concern that there children are not meeting these milestones, then parents are asking physicians and physicians are directing them to their educators," Chancellor said.