There are three kinds of midwives to choose from in the USA.
Nurse-Midwives: A certified nurse-midwife goes through nursing school and then goes on to receive separate midwifery post-graduate certification. Most nurse-midwives work in hospitals with less than 10% attending home births.
Certified Midwives: Certified professional midwives receive their credentials from the North American Registry of Midwives.Certified direct-entry midwives go to school at the American College of Nurse-Midwives, but lack the additional nursing degree of a certified nurse-midwife.
Lay Midwives: Lay midwives may have state licensing -- as provided by 27 states in the USA, or may be knowledgeable and educated in midwifery without a license in one of the 23 states that fails to licence midwives.
A majority of US home births and birthing center births, on the other hand, are attended by entry-level midwives who may or may not be certified.