A study by the Employee Benefit Research Institute reports a recent law that requires group health plans and insurers to make dependent coverage available for children up to age 26 will increase employment-based coverage by estimates ranging from 680,000 to 2.12 million individuals.

However, EBRI states there is reason to believe estimates understate the size of the population that might enroll in their parents' employment-based coverage, and the costs of the mandate are expected to increase health insurance premiums 1 percent by 2013.

EBRI lists several factors for the premium hike, including:

• Shortcomings in regulatory assumptions that the 2.6 million 19- to 25-year-olds in states that already allow them to enroll in extended coverage are unlikely to enroll under PPACA.
• It is largely impossible to factor in parents' decisions when it comes to enrolling their children
• Contrary to regulatory assumptions, about 3 million of the 7.5 million 19- to 25-year-olds with some other form of coverage (such as Medicaid or Tricare) will be eligible to enroll in the PPACA program
• More adult children are likely to become eligible as they gain employment.

The report characterizes the uninsured age 19 to 25 population as more likely to be male, older, Hispanic, and less physically and mentally healthy, the study says. It was also determined that the uninsured population is less likely than the population with employment-based health coverage to use preventive health services, to exercise, and to be of normal weight. The uninsured are more likely to smoke and more likely to have asthma.