LOS ANGELES, Dec. 1 (Xinhua) -- More than half a million U.S. children have autism, taking a major financial toll on their families, a new study showed.

    Families with autistic kids pay more for the kids' health needs, spend more time providing or arranging for that care, and are more likely to have money difficulties, according to the study by researchers at the government's Maternal and Child Health Bureau.

    Compared with parents whose youngsters have chronic health care needs but not autism, those with autistic children are three times more likely to have to quit their jobs or reduce work hours to care for their kids, said the study appearing in the December issue of Pediatrics.

    "This is the first national survey that looked at the impact on families of having kids with special health care needs," said lead author Michael Kogan.

    The researchers conducted a nationwide survey of nearly 40,000 children with special health care needs between 2005-06. These children have a broad range of chronic conditions, including physical and mental illness, requiring more extensive than usual medical care.

    A total of 2,088 children with special health needs had autism, which translates to about 535,000 kids aged 3 to 17 nationwide, the study authors said.

    Children affected with autism often need many more types of treatment than kids with other chronic conditions, including speech and behavior therapy and sometimes medication.

    Kogan said that may explain the disproportionate strain on their families.