The autism prevalence rate among children in the United States has risen for the first time in four years, according to new data released Thursday by the Centers for Disease Control and Prevention.

While the reasons for the increase aren't fully known, some CDC experts say it may be due in part to increased awareness and outreach, particularly to communities of color, in which children are believed to have been historically underdiagnosed.

Yet the reports also make clear that too many children are not getting an early enough diagnosis and critical services for autism spectrum disorder, a wide range of development issues including difficulties in social interactions and communication, as well as repetitive behaviors.

In the new study, the gap between white children and their African American and Latino peers narrowed, suggesting that more children of color with autism are being identified – the first step, experts say, in getting youngsters the help they need to achieve their full potential.

The new report by the CDC's Autism and Developmental Disabilities Monitoring Network in 2014 examined autism diagnoses of 8-year-old children  in 11 states, including New Jersey, and estimated that one in every 59 children were identified as having autism. In 2012 and 2010, the prevalence at that age was one in 68.

While the network's reports are based only on data from participating states, the results are widely considered to reflect broader national trends.

"Autism prevalence among black and Hispanic children is approaching that of white children," said Stuart Shapira, associate director for science at the CDC's National Center on Birth Defects and Developmental Disabilities.

In the previous report, which contained 2012 data, white children's autism prevalence was 20 percent higher than that of black children. In the new report, white children's rate is about 10 percent higher, Shapira said. Also in the previous report, white youngsters had a 50 percent higher incidence than their Hispanic peers, but it's only 20 percent higher in the new report.

"The higher number of black and Hispanic children now being identified with autism could be due to more effective outreach in minority communities and increased efforts to have all children screened for autism so they can get the services they need," Shapira said.

Shapira said there is no known biological basis for the incidence disparities among different racial and ethnic groups.

Girls are diagnosed much less often than boys, in part, say experts, because the disorder may express itself differently, making it easier to overlook or discover later in females.

In the new report, New Jersey continued to have the highest prevalence of autism among the 11 states – 2.9 percent of its 8-year-olds were estimated to be diagnosed with the disorder compared with 1.7 percent of the participating states overall. In the Garden State, the new rate is one in 34 children, compared with one in 41 in the prior report. Those differences, experts say, may be due to how autism is diagnosed and documented in the different states. Pennsylvania does not participate in the survey.

Thomas Frazier, chief science officer for Autism Speaks, a national advocacy organization, called the overall 15 percent rise in prevalence "a truly significant increase that says we need to keep up the push" for more services and research into what has been called the nation's fastest-growing developmental disability.

He called the new rate "a conservative estimate" of the actual incidence of autism nationally.

Walter Zahorodny, an associate professor of pediatrics at Rutgers New Jersey Medical School who directed the New Jersey portion of the study, called the results "startling."

"It is now clear that what we saw in 2016 was just a pause along the way," Zahorodny said. "It remains to be seen at what point rates will plateau. There are still undefined environmental risks which contribute to this significant increase, factors that could affect a child in its development in utero or related to birth complications or to the newborn period. We need more research into non-genetic triggers for autism."

Frazier said all children should receive a full developmental screening, including for autism, at ages 18 to 24 months. If a diagnosis is made, the child should be referred to appropriate treatment early for the best possible outcomes.

The CDC study suggests not enough children are being screened that young.

Fewer than half of the children surveyed got their initial diagnoses by age 4. In addition, although 85 percent of the children had developmental concerns noted in their health reports by age 3, only 42 percent of them had received an actual developmental evaluation by that age.

Natasha Houston-Hurst, a Philadelphia mother who works with special-needs adults, said her son Tyler Pembleton, 6, was diagnosed with ASD at age 4. She had expressed concerns to a health-care provider three years before and was told he was too young for testing. Before the diagnosis, Houston-Hurst was told her son probably wouldn't speak and would have only limited development.

Tyler is now a talkative, active boy who reads above grade level. He receives therapies to help him thrive despite disabilities that include vision problems. Houston-Hurst pushed to get her son those services.

She believes some parents, especially other African Americans, may be "in denial" about autism symptoms.

"They'll look at them and say, 'He's just being bad, he's not listening,' " she said.

All parents, she said, need to persist.

"You have to be your kid's biggest advocate," Houston-Hurst said. "You've got to fight for your kid."