I believe that a key component that every doula should have is Neonatal Resuscitation. See how to get formal training here.
Even if a doula chooses to not get NRP certified, I highly recommend that she read through the course material and then test that knowledge through the printables here and the additional information found here:
Why do I think we need to know this information as doulas? Consider that we work with women during childbirth. Consider also that many of us encourage the mother's that we work with to stay at home as long as possible or comfortable.. consider finally that some labors progress very rapidly and, for that, many of us are also learned in emergency childbirth.
Wouldn't it stand to be reasoned, then, that we should also train ourselves and be prepared to help in the event that one of the babes that we *might* help birth *may* need extra help to initiate respiratory efforts? Consider becoming NRP certified, or at least educated, as part of your celebrations during the month of May, International Doula Month.