A CPM or lay midwife only goes through a short program and then takes a test, but has no nursing background and may not have any experience with healthcare.
Just for further clarification,
a CPM and lay mw are not the same thing. Lay midwives may have no formal certification, whereas CPM's do.
There are really three main categories of mw's:
1. CNM's;
2. non-nurse midwives with some sort of certification (
CPM's, liscensed mw's, etc. - it can vary according to program, state you are in, etc. CPM's must take the NARM exam for certification.
3. lay midwives "The term "Lay Midwife" has been used to designate an uncertified or unlicensed midwife who was educated through informal routes such as self-study or apprenticeship rather than through a formal program. This term does not necessarily mean a low level of education, just that the midwife either chose not to become certified or licensed, or there was no certification available for her type of education (as was the fact before the Certified Professional Midwife credential was available)."
It can be really confusing!
This is a GREAT page of midwifery definitions:
http://www.mana.org/definitions.html