After the Affordable Care Act was passed in 2010, an estimated 13.7 million young adults between the ages of 19 and 25 stayed on or joined their parents' health plans.

That's one of the findings from a survey conducted by the Commonwealth Fund, a New York-based private foundation that supports health care coverage.

The 13.7 million that stayed or joined between November 2010 and November 2011 included 6.6 million young adults who likely would not have been able to do so prior to the passage of the Affordable Care Act, the survey showed.

The new law requires insurance plans that include dependent coverage to cover adult children until their 26th birthdays.

Of the 1,863 survey respondents, 60% said they did not get health care because of cost and half reported problems paying medical bills or said they were paying off medical debt over time.

The survey found that nearly two of five (39%) young adults ages 19 to 29 were without health insurance for all or part of 2011.

Young adults in low- and moderate-income households – considered to be those least likely to have access to parents' plans – were the most at risk, according to the survey: 70% of young adults with incomes under 133% of poverty ($14,484 for a single person and $29,726 for a family of four) had a gap in their insurance in 2011.

Overall, two of five (41%) young adults said they had not gotten health care because of cost in the past year; the rate rose to 60% among uninsured young adults. More than one-third (36%) of all young adults reported problems paying medical bills or said they were paying off medical debt over time; the rate was 51% among uninsured young adults.

Among young adults who reported problems paying medical bills or said they were paying off medical debt, 43% said they had used up all their savings to pay their bills, 33% took on credit card debt, 32% had been unable to meet other debt obligations such as school loans or tuition payments, 31% delayed education or career plans, and 28% said they had been unable to pay for basic necessities like food or rent.

Nearly six of 10 (59%) young adults ages 19 to 25 were aware that that they could stay on or join their parents' plans under the Affordable Health Care Act.