More evidence that free health care is worth protecting. Under Obama's Affordable Care Act, there was an option to increase Medicaid coverage, to include for example contraception, and pregnancy and maternity care. Thirty one states agreed this option; the other 19 declined, thus creating a natural experiment. Infant mortality went up (albeit slightly) in the 19 that declined, and went down in the other 31. The difference was greatest for African Americans.
Of course this is observational data, and the states which declined the expansion were an interesting group, politically and socially.