A new report shows the number of children who lack health insurance coverage rose for the first time in a decade from 2016 to 2017, with an advocate saying the drop should raise alarm bells about the potential for further decreases in coming years.

Many states have sought to increase coverage for children in recent years, resulting in steady improvement through 2016, when there were 3.6 million uninsured kids in the country—a historic low. But last year saw a reversal, with data collected by the U.S. Census Bureau showing 3.9 million uninsured children, according to the report by Georgetown University’s Center for Children and Families.

Joan Alker, executive director of the center, said she was particularly alarmed because the growth of around 276,000 more uninsured children came at a time when the economy is strong.

“With an improving economy and a very low unemployment rate, the fact that our nation is going backwards on children’s health coverage is very troubling,” Alker said. “Without serious efforts to get back on track, the decline in coverage is likely to continue in 2018 and may in fact get worse for America’s children.”

Along with the national trend, the center found that nine states showed notable increases in the rate of uninsured children living there: South Dakota, Utah, Texas, Georgia, South Carolina, Florida, Ohio, Tennessee and Massachusetts.

Texas had the highest uninsured rate in the country, with 10.7 percent of children lacking coverage. But Carrie Williams, a spokeswoman for the state’s Health and Human Services Commission, noted that the state has seen significant improvement in the share of uninsured children, which dropped dramatically from more than 18 percent in 2008.

Courtesy of Georgetown University Health Policy Institute's Center for Children and Families

The center found that the number of children covered by their parents’ insurance from employers rose between 2016 and 2017, but coverage in Medicaid and state CHIP programs dropped. Medicaid provides coverage for children from the poorest families, while the Children’s Health Insurance Program allows states to offer insurance for kids from families with higher incomes.

No state showed any progress in chipping away at the uninsured rate for children.

“Think of a child with asthma who needs doctor visits and medications to keep her allergies and asthma under control and without that help will wind up in the ER and missing school,” Alker said. “Kids need healthcare to succeed.”

Courtesy of Georgetown University Health Policy Institute's Center for Children and Families

The center’s research shows that many of the uncovered children are actually eligible for Medicaid and CHIP in their states, providing an opportunity for states to make an effort to inform people about the offerings and keep them enrolled each year when they need to renew, Alker said.

While it is unclear what exactly led to the decrease last year, Alker said one factor could be the drumbeat of negative news about the Affordable Care Act, particularly Republican efforts to repeal the law, along with news reports about uncertain federal CHIP funding. While CHIP expired in the fall of 2017, it wasn’t reauthorized until early 2018.

Over the past couple years, the Trump administration has cut funding for the navigators who have helped people sign up for health insurance through the ACA’s marketplaces. NPR reported this week that funding is at $10 million this fall, compared to $36 million last year and $63 million in 2016.

Alker noted that in the past, those navigators have often helped people get their kids insured through Medicaid or CHIP, although that wasn’t their primary purpose.

The report also found that three-quarters of children who aren’t covered live in states that haven’t expanded Medicaid through the ACA.

If those states did expand Medicaid to more people, the increased coverage for adults—in many cases of the parents of the uncovered children—would likely result in more kids getting enrolled as well, she said. “That is the one surefire way to move this number in the right direction,” Alker said.