The number of Americans without health insurance swelled to 11.3 percent during the first quarter 2017, compared to 10.9 percent in the third and fourth quarters of 2016, according to a Gallup-Healthways poll.
The 11.3 percent represents a record low since Gallup and population health company Healthways began tracking insurance coverage in 2008.
Despite an uptick in the uninsured rate in the first quarter of 2017, the number of adults without health insurance is still 6.7 percent lower than it was at its peak in the third quarter of 2013, when it was 18 percent.
This was just before the health insurance exchanges opened in October 2013 and the Affordable Care Act required individuals to obtain coverage or face a tax penalty.
Gallup speculated the difference in the insured numbers this year over last has to do with consumers' uncertainty over getting coverage through the ACA.
Humana and several other insurers have announced they will exit some or all health exchanges in 2018.
Republicans have proposed an amendment to the American Health Care Act, a bill that House Speaker Paul Ryan withdrew last month when it became clear it didn't have the votes to pass. If the amended bill goes through, it would replace the ACA and potentially move the exchange markets to state control in three years.
The total number of people signing up for ACA coverage through Healthcare.gov this past enrollment season dropped by 400,000 consumers, from 9.6 million last year to 9.2 million this year.
The number of Americans in self-insured plans has grown by 3 percent since the last quarter of 2013.
Medicaid shows the second-largest increase among insurance sources, a 2 percent rise likely due to the ACA's Medicaid expansion.
The percent of people uninsured has dropped sharply among young adults since 2013, according to Gallup, when the ACA began the individual mandate to get coverage or face a tax penalty. The ACA also allowed young adults to remain on their parents' plan up until age 26. This could account for the more than 7 percent decline in uninsured adults aged 18 to 25, since 2013, Gallup said.
Those aged 26 to 34 have seen a nearly 10-point drop, according to Gallup.
"Young adults represent a critical group in a well-functioning healthcare market, since their premiums help offset the higher costs of older Americans who typically use more medical services," Gallup said.
The Gallup-Healthways Well-Being Index results for the first quarter of 2017 are based on 44,596 interviews from Jan. 2 to March 31.
Uninsured rates have fallen substantially among Hispanics and lower-income Americans -- the two groups with the highest uninsured rates before the mandate to carry insurance took effect. Although the uninsured rate among Hispanics remains the highest of any major racial or ethnic group, at 28.6 percent, it is down 10.1 points since the last quarter of 2013, according to poll results.
By comparison, the uninsured rates for non-Hispanic black and white adults have fallen by 8 and 5 percent, respectively. The rate among lower-income adults has dropped nearly 9 percent, outpacing the 3.2 percent of middle-income Americans and the 2.4 percent high-income adults.
Americans' opinions of the ACA have improved since last fall, with a majority approving of the law for the first time.