Experts say better diagnostic testing is part of it.

The prevalence of autism spectrum disorder (ASD) in the United States has jumped again — but the real story is behind the numbers.

About 1 in 59 children in the United States have ASD, according to the latest data from the Centers for Disease Control and Prevention (CDC). It’s four times more likely to occur in boys than in girls.

The data are drawn from a 2014 survey of 325,483 children in 11 different states, conducted by the CDC’s Autism and Developmental Disabilities Monitoring (ADDM) Network.

The results of the 2014 survey show a 16 percent increase in the total prevalence of ASD compared with the previous survey, which was conducted in 2012.

During that time, the rate of autism prevalence was 1 in 68 children. This is a major jump in the rate from 2000, when it was just 1 in 150 children, according to the CDC.

However, experts say that the increasing prevalence of ASD in the CDC’s latest report has more to do with better monitoring and diagnosis of the disorder, rather than a de facto rise in the number of children who have ASD.

“We’re getting better at identifying under-unidentified populations, so it’s not as if the numbers are rising. It’s more that everyone is going to the number that it should be,” Dr. Max Wiznitzer, a pediatric neurologist at University Hospitals Rainbow Babies and Children’s Hospital in Cleveland, Ohio, told Healthline.

Historically, rates of ASD in the United States have been highest among white children compared with black or Hispanic children.

In 2006, for example, the prevalence of ASD among white children was 30 percent higher than black children, and nearly 70 percent higher than Hispanic children.

This didn’t make a lot of sense, said Wiznitzer.

Doctors questioned why the disorder would so disproportionately affect one ethnic group of children. What they discovered was that ASD prevalence tends to be higher among residents of neighborhoods with higher socioeconomic status. These residents are more likely to have access to quality healthcare.

In the CDC’s latest report, the diagnostic gap between white, Hispanic, and black children has shrunk significantly, indicating that more diagnoses are occurring among typically underdiagnosed ethnic populations.

According to the data, the difference in ASD prevalence between white children and black children is now only 7 percent. The difference between white and Hispanic children has also shrunk to just 22 percent.

“If you sample a larger amount of records, it expands the ability to identify these individuals, and the fact that they are getting better at the populations where traditionally the numbers have been lower, which made no sense,” said Wiznitzer.

Even if ASD prevalence is up, the study authors caution that the results of the survey shouldn’t be taken to represent the United States as a whole. ASD prevalence varies significantly based on geographic location, which may indicate which people have access to care rather than the actual numbers of children developing ASD.

In particular, surveillance areas closer to diagnostic centers tend to have higher ASD prevalence.

The ADDM surveillance site in Arkansas reported the lowest prevalence at just 1.31 percent, while New Jersey had the highest at 2.93 percent. New Jersey also exhibited almost no difference in ASD prevalence between ethnic groups.

Experts believe that access to quality healthcare in New Jersey is likely the predominant factor for its higher rates of ASD compared to other cities.

For parents concerned about the seeming continual rise in ASD rates across the country, Wiznitzer cautions: “Read the small print. Ask why this happened.”

He also points out that there are other conclusions to be drawn that are more significant than ASD prevalence.

In the past several years, there has been an increased pressure to diagnose ASD as young as possible. The earlier the diagnosis, the better the outcome.

The age at which most children receive an ASD diagnosis is still around 4 1/2, and that number has seen very little decrease over the past decade. Despite advances, many children are probably receiving diagnoses later than they should.

“That to me is the more concerning number,” Wiznitzer said.

“The age of identification hasn’t dropped, significantly. That means that there is the potential for not being able to implement effective strategies for this population at as young an age as we possibly can,” he said.