The number of kids enrolled in Medicaid and the Children’s Health Insurance Program (CHIP) — two government health plans for the poor — fell by nearly 600,000 in the first 11 months of 2018, a precipitous drop that has puzzled and alarmed many health policy analysts, while several states say it reflects the good news of an improving economy.

Enrollment in the two programs decreased by 599,000 children in the 48 states from which the U.S. Centers for Medicare and Medicaid Services (CMS) has data from December 2017 to November 2018, the last month for which numbers are available. At the beginning of that period, Medicaid and CHIP enrolled nearly 36 million children in those states.

Read more at PewTrusts.