Childbirth broadly describes the final stage of pregnancy where a baby (or babies) leave the mother through either vaginal delivery or caesarian section. Both obstetrics and midwifery deal with childbirth. Obstetrics is the field of medicine and obstetricians are medical doctors specializing in woman's health, pregnancy, and labor and delivery. In the United States, most obstetricians train for at least 11 years, including four years of medical school, four years of residency training, and three years of fellowship training. Midwifes in the United States can receive credentials in three categories: certified professional midwife (CPM), certified midwife (CM), or certified nurse midwife (CNM). CM credentialing requires post-graduate degree in midwifery while CNMs are registered nurses (RN) with master's or doctoral degrees in nursing. Midwifes are trained to manage low-risk pregnancies. Obstetricians care for woman with high-risk pregnancies, such as multiple baby births and women with pre-existing conditions, and they are surgically trained to perform Cesarean sections which can be scheduled, unplanned, or emergency surgeries.