The market is deciding, right now. People choose whether to use a midwife or an OB, based on multiple factors, one of which is cost. What percentage of births are handled by midwives now? What will the percentage be, if the cost is arbitrarily increased?
Not in hospitals, I promise you. Physicians' organizations have suppressed all sorts of competitors via their political clout, whether chiropractors, PAs, or nurse-practitioners. They've even used that clout to divert funds for education of their competitors at state universities.
It's political restraint of trade. There was even a SCOTUS ruling against the American College of Surgeons on the topic.