Despite a requirement that insurers start covering behavioral health treatment for individuals and small groups, a new analysis suggests less than half of states plan to include autism therapy.

Many autism advocates were hopeful when the Affordable Care Act was passed in 2010 that insurance coverage for behavioral therapy used to treat the developmental disorder would be mandated nationwide. Under the law, insurance providers are required to include 10 types of care — including behavioral health treatment — in all plans offered to individuals and small groups starting in 2014.

However, what falls under each of the required categories was largely left to the states to determine. Now it looks like many states may choose not to mandate ABA therapy coverage.

In a review released this month by Autism Speaks, the group found that 18 states have specified coverage of applied behavior analysis, or ABA, therapy in plans for their health insurance exchanges, according to summaries of state proposals from the U.S. Department of Health and Human Services’ Center for Consumer Information and Insurance Oversight.

Another four states did not specifically include ABA therapy coverage in their submissions, but language within the plans suggests the states may intend to require the treatment, according to the analysis.

Though technically the requirements will only impact health plans for individuals and small groups, Stuart Spielman, senior policy adviser for Autism Speaks, said that if ABA coverage is mandated, there would likely be a ripple effect on health insurance provided by large employers as well.

“While the picture remains somewhat murky, the unequivocal support needed by families dealing with autism clearly is missing,” said Spielman who indicated that health insurance alone without coverage of ABA does too little to address the needs of a rising number of Americans with autism.

According to the advocacy group’s analysis, ABA coverage is included in plans submitted by Arizona, Arkansas, California, Connecticut, Indiana, Kentucky, Louisiana, Maine, Massachusetts, Missouri, Montana, Nevada, New Hampshire, New York, Texas, Vermont, West Virginia and Wisconsin. What’s more, the governor of Ohio indicated late last year that his state would also include ABA and autism therapies in its essential benefits and Michigan officials have signaled similarly.

Meanwhile, plans from Colorado, Illinois, New Jersey and New Mexico leave it unclear whether ABA is expected to be covered, the review said. And, based on currently available information, it’s uncertain what will happen in the remaining states.

Federal regulations governing what must be included within each state’s essential health benefits are expected to be finalized next month. Officials at Autism Speaks say they remain optimistic that the Obama administration will require all states to include coverage for ABA therapy within the final rules.