Depending on the setting (hospital, hospice, birthing center, home) a pregnant woman will have access to medical staff of various types. The most common today is an Obstetrician (OB) and birthing staff consisting of nurses specifically trained in childbirth; birthing centers and home births often make use of registered Midwives. All birthing staff have a level of medical expertise and education.
In a hospital setting, the nurses are the most important part of the birthing process aside from the obstetrician, who generally oversees and (normally) delivers the actual baby. The nurses monitor the mother's health, use their knowledge to determine pain levels and possible health risks, and administer medication based on the OB's prescription.
While nurses cannot order medication of their own volition, they have a certain amount of leeway to take action if the mother or baby are in direct danger; Nurse Practitioners do not usually oversee childbirth, but when they do, they have the ability to order medication and take other, higher authority actions. Nurses are present during every part of the labor process, and provide medical action, verbal and mental support, counseling, and general health management. Nurses also attend to the basic care needs, such as sterilization, cleanliness of the area, and patient transfer.
Most nurses who assist in childbirth are trained specifically in that area, and their skills fall under various medical functions; an L&D nurse assists general, uncomplicated labor; an Antepartum nurse specializes in birthing complications; a Postpartum nurse does not assist with the birth directly, but cares for the mother after the birth has occurred (nursesource.org).