If you are pregnant or thinking of becoming pregnant, you have probably spent some time worrying about autism. You may have heard that autism is an epidemic. Back in the 1970s, autism was considered very rare. It was thought to affect only about one child out of 2,000. Today it may affect one to two children out of 100. That sure sounds like an epidemic. But it probably isn’t. [1,2]
Autism has always been surrounded by myth and mystery. But as the mystery unravels, the myths drop away. The autism epidemic is probably the latest myth to bite the dust. A growing body of solid research is showing that although autism is being diagnosed more frequently, the actual number of children who have the symptoms is remaining constant worldwide at about 1 to 2 percent. [1,2]
Most recently, a large population study done in Sweden and published in the medical journal BMJ, found that there was no evidence of an actual increase in autism symptoms over 10 years in children born between 1993 and 2002. The study included over 1 million children. The researchers concluded that changes in the way autism was diagnosed accounted for an increased number of diagnoses, but the symptoms of the children remained stable. 
Autism Myths Through History
Autism was first described in the mid-1940s. One of the first myths was that autism was a psychiatric disease caused by frigid, withdrawn, “refrigerator” mothers. Children were removed from homes to be treated. Of course, we now know that autism is a brain development disorder that has nothing to do with parenting. [3,4]
In the 1950s and 60s, autism was thought to be a form of childhood schizophrenia. It was not until 1980 that the American Psychiatric Association’s diagnostic manual (DSM-III) separated autism form schizophrenia. [3,4]
At the beginning of this century, many people were convinced that autism was caused by vaccinations. Parents noted that autism started soon after vaccinations started. But many vaccinations are given at about the age when autism symptoms begin. There have now been enough studies that debunk that myth. While it is possible that vaccinations may trigger autism genes in some children, the Institute of Medicine can say confidently that vaccines are not a significant cause of autism. 
So Why the Increase in Diagnosis?
As the diagnosis has changed over the years, many more children now fit into it. In 1994 (DSM-IV) the diagnosis was expanded to include Asperger syndrome. Asperger syndrome is a type of high functioning autism. That change let a lot more children under the autism umbrella. [3,4]
In 1980 (DSM-III) there were 6 diagnostic criteria that needed to be met for the diagnosis. A child needed 6 out of 6 to be diagnosed. Today there are 16 diagnostic criteria. A child needs to meet 8 out of the 16 to be diagnosed. As we have become more aware of the spectrum of autism, many children previously diagnosed with other types of disabilities are now recognized as having autism. [3,4]
In short, there is probably no epidemic of autism. There is more awareness of the disorder and a better way of diagnosing it. We now know that autism is a group, or spectrum, of disorders. They are characterized by deficits in social communication and interaction and inability to adapt behaviors. 
Symptoms may begin as early as 18 months and most children can be diagnosed by age 2. Here are some early symptoms to talk to your child’s doctor about: 
- Failure to make eye contact
- Not looking at objects when you point
- Not responding to your voice
- Not responding to hugs or cuddles
- Repeating sounds or movements over and over
- Having severe reaction to touch or sounds
The good news is that better diagnosis means earlier diagnosis and better treatment outcomes. 
- BMJ, Autism phenotype versus registered diagnosis in Swedish children: prevalence trends over 10 years in general population samples.
- Scientific American, Is There Really an Autism Epidemic?
- Medical News, Autism History.
- New England Journal of Medicine, Autism at 70.
- CDC, Facts About ASD.