^ Just a little correction. Doulas are not allowed to talk to the medical staff directly, but they will talk to you and remind you what you had on your birth plan. For example, they won't tell the nurse " she didn't want an epidural", but will ask you "hey, remember, you really didn't want an epidural. You know you can do this without it, you were pretty sure of it when we talked before labor".
I think it's really helpful because when you're in pain and exausted, you're vulnerable and after a certain point, you just don't care and say yes to anything that could make your life easier. However, once it's done, you regret it.