A New York Times story about the prosecution of an Indiana midwife notes that 10 states still prohibit birth assistance by anyone other than a doctor or nurse. In those states it is legal to give birth at home, but it is illegal to hire anyone without one of the requisite medical degrees to help you, and people who have those degrees tend to insist on hospitals or birthing centers attached to hospitals.
Reason has been following this issue for many years: Sarah Foster made the case for decriminalizing midwifery in the September 1982 issue; a decade later, in the March 1992 issue, Archie Brodsky took a fresh look at the legal barriers to midwifery. (Neither issue, unfortunately, is available online yet.) For a more recent update, check out Midwifery Today.