Obstetrics is the medical specialty of caring for pregnant women.  Physicians who specialize in obstetrics are called obstetricians.  They provide care throughout the nine months of pregnancy, oversee the labor and delivery process, and care for the new mom while she is in the hospital.  A certified nurse midwife (CNM) is also a medical professional who specializes in pregnancy.  These providers are not physicians and therefore do not perform obstetrical surgery.  If a woman's pregnancy is normal and uncomplicated, she may choose a midwife for her prenatal care, labor, and delivery.  Gynecology is the specialty of diagnosing, treating, and preventing diseases of the female reproductive organs, including uterus, vagina, and ovaries.  Physicians who specialize in gynecology are called gynecologists.  Most gynecologists in the United States are also obstetricians, and vice versa.