Gynecology is the medical practice dealing with the health of the female reproductive system (uterus, vagina and ovaries). Literally, outside medicine, it means "the science of women."
Obstetrics is the medical specialty dealing with the care of women's reproductive tracts and their children during pregnancy (prenatal period), childbirth and the postnatal period. Many obstetricians are also gynecologists, meaning they perform in both specialties. In the United States, these physicians are commonly referred to as OB-GYNs.