WASHINGTON » The number of young adults without health insurance has dropped significantly, a new survey finds, thanks to a provision of President Barack Obama’s health care law allowing them to stay on their parents’ plans.

The new Gallup poll findings translate to about 1 million more young adults with health insurance.

While the bleak economy has made it hard for young people trying to enter the workforce, fewer are being forced to also go without medical care.

A Gallup survey released today finds that the share of adults ages 18-25 without health insurance dropped from 28 percent starting last fall to 24.2 percent in the second quarter of this year. That defies the disheartening trend of rising numbers of working-age Americans without coverage.

"While we did not see a drop-off in any other age group, we did see a drop in this age group," said Frank Newport, Gallup’s polling director.

Public opinion remains divided about Obama’s health care overhaul, but coverage for young adults has proven to be a popular and relatively low-cost benefit that families were eager to sign up for in these days of prolonged school-to-work transitions.

Health and Human Services Secretary Kathleen Sebelius planned her own announcement Wednesday about health insurance for young adults. A Census report last week hinted at an increase in coverage.

The new law allows adult children to remain on a parent’s plan until they turn 26, a provision that technically took last effect last fall but wasn’t implemented by most workplace health plans until Jan. 1.

"The big change started in the last quarter of 2010 and continued further in the first two quarters of this year," said Newport. "Bingo, it started going down."

Young adults — sometimes termed the "invincibles"— are still more likely to be uninsured than any other age group.

Some are making the switch from school to work. Others are in low-wage jobs that don’t usually offer coverage. And some pass up workplace health insurance because they don’t think they’ll use it and would rather get a little extra in their paychecks.

Census figures show nearly 35 million people are in the 18-25 age group, so Gallup’s 4 percentage-point drop would translate to an increase of roughly 1 million or more getting health insurance.

The Gallup findings are in line with other reports. A survey of employers this summer by Mercer, the benefits consulting firm, found a 2 percentage-point increase in health plan enrollment as a result of extending coverage to workers’ young adult children. Young adults are generally inexpensive to cover. Some companies have spread the extra premiums among their workforces.

Before the health care law passed, many employers automatically cut off dependents upon graduation from college or high school. Repealing Obama’s law, as Republicans seek to do, would eliminate the requirement for companies to provide extended coverage for young adults.

Other early coverage expansions in the health care law have not worked as well.

A program that offers health insurance to people turned down for private coverage because of a health problem has seen disappointingly low enrollment, a consequence of high premiums. The main push to cover the uninsured under the new law won’t come until 2014. At that time, more than 30 million people are expected to get coverage through a combination of expanding Medicaid and providing tax credits to make private insurance more affordable.

Gallup surveys nearly 1,000 people daily. This analysis includes 89,857 respondents interviewed between April 1 and June 30. The margin of error for the full sample is plus or minus 1 percentage point; it is higher for subgroups.