A new report from the Centers for Disease Control shows that 1 in 59 children have been diagnosed with an autism spectrum disorder in the United States. That’s a 15 percent increase from the most recent report two years ago. 

Researchers at Johns Hopkins University contributed to the study. They say autism rates have been rising since the 1960s, but they don’t know how much of the rise is due to an increase in actual cases. They cite other factors that may be contributing, such as: increased awareness, screening, diagnostic services treatment and intervention services, better documentation of ASD behaviors and changes in diagnostic criteria.

Autism Speaks said other possible reasons for the increase in prevalence may include that more people are having children later in life and that older parents have a higher risk of having a child with developmental disorders and other risk factors during pregnancy.

Boys are four times as likely as girls to be diagnosed with autism.  The rate is one in 38 among boys and one in 152 among girls.