The Medicaid report said that almost 10.8 million extra people had signed up in that program and the related Children's Health Insurance Program compared to the period just prior to the launch of the Obamacare exchanges, an 18.6 percent increase in average monthly enrollment during that time frame.
By the end of December, a total of nearly 69.7 million people were enrolled in Medicaid and CHIP nationally.
And again, the biggest gains in Medicaid enrollment came in states that had loosened eligibility restrictions on the program as allowed by Obamacare.
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States that have allowed nearly all poor adults to enroll in Medicaid saw a more than 27 percent increase in their Medicaid rolls, on average since last summer 2013, while those that didn't expand eligibility had an average increase of just above 7 percent.
Currently, 28 states and the District of Columbia have expanded Medicaid, while the remaining states have tougher restrictions on who can participate.
Robin Rudowitz, associate director for Medicaid and the uninsured at the Kaiser Family Foundation research group, said "It's a little bit hard to disentangle" how many of the new Medicaid enrollees were previously eligible but hadn't bothered to sign up before, and how many were newly eligible because their states had expanded the eligibility guidelines.
And "we also similarly don't have an estimate of how many of these new people were previously uninsured," Rudowitz said.
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The launch of the Obamacare exchanges in the fall of 2013 has been credited with boosting Medicaid sign-ups. Although the exchanges sell private health insurance plans, many people became aware they could get Medicaid, which as a rule doesn't cost them anything, when they entered income data on the Obamacare exchange's application forms.
Another factor credited with driving Medicaid enrollment is the Obamacare rule requiring most Americans to have some form of health coverage or pay a fine.