According to a new report from Georgetown University’s Center for Children and Families, the percentage of children without health insurance grew in 2017 after years of decline.

The report said 276,000 more children did not have health insurance last year, increasing to 3.9 million in 2017 from 3.6 million in 2016. The latest measure represents 5% of children in the U.S. While not a huge increase from 4.7% the year before, it’s still viewed with concern.

The report’s authors note this is the first time in nearly a decade that the number of uninsured children increased, which is uncommon in periods of economic growth. “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,” said Joan Alker, the center’s executive director. “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.”

Alker and the other authors suggest the rise can be attributed to several reasons, with most, if not all, tied to the Trump administration and a Republican-controlled Congress. There have been attempts to repeal the Affordable Care Act, also known as Obamacare, and the successful reversal of the individual health insurance mandate. Additionally, the report cited the Trump administration’s decision to cut funding for Obamacare navigators who help people choose and sign up for their insurance plan.

Another likely cause of more uninsured children is shrinking Medicaid coverage for low-income adults, the report said. Three-quarters of children who lost coverage live in states that did not expand Medicaid and studies suggest that children are more likely to be insured when their parents are covered. A number of states, including South Dakota, Utah, and Florida, saw statistically significant increases in their rate of uninsured children. Texas had the largest share of uninsured children, where more than one in five uninsured children live.

For a number of months in 2017, Congress failed to approve funding for the Children’s Health Insurance Program, or CHIP, which threatened children’s coverage in several states. And finally, the authors note the threat of a Trump administration proposal that would make it harder for legal immigrants to get green cards if they receive public assistance may have discouraged them from applying for Medicaid out of fear of losing their status in the U.S.

Overall, the report found the share of children with employer-sponsored coverage in 2017 increased—a reflection of a strong economy. That was not the case for those who would be covered by the other programs previously mentioned, such as Medicaid, CHIP, or plans bought on the Obamacare exchanges.