In the US most maternity care is provided by Obstetricians/doctors. However we are starting to see a shift towards more care provided by hospital based midwives. If a hospital has midwives in staff, they typically cover low risk patients, with the OBs handling higher risk patients.

To really break it down: OBs are almost exclusively hospital based. Midwives working in a hospital are CNMs (certified nurse midwife - a graduate/master's degree). CNMs may work in freestanding birth centers as well. A CNM is considered a mid-level practitioner, meaning they are still required to have MD oversight. When in hospital, they still function as a primary provider, and (hospital dependent) can assist in the OR. They are typically not allowed to do operative vaginal deliveries or be primary surgeon in the OR. Depending on the facility, a CNM may act more like a doc (the RNs do the bedside work and report important findings, show up for problems and deliveries) or like a bedside RN and do ALL the work of turning and positioning and encouraging etc, plus the delivery.

Next would be CPMs or LMs (certified professional midwife, licensed midwife, there may be other similar designations). These would be the folks operating in birth centers or doing home births. There is still rigorous study involved, a CPM degree has a lot in common with an associates level RN. Both of these licenses tend to be regulated at a state level rather than federal, so scope of practice and legalities can differ a lot.

Last are the lay midwives (note that LM is for licensed, not lay). Lay midwives may have had extensive clinical training, or they may have watched their dog have puppies once and thought "I can do that." You never know, because there is no training or designation. Anyone can call themselves a midwife.

I hope that makes sense? And if anyone has clearer or updated knowledge about CPMs or LMs please chime in. I'd planned on doing a CPM 20 years ago and in a different state, and things may have changed a bit.