The female reproductive system is the focus of the medical specialty of gynecology. Doctors who specialize in obstetrics and gynecology undergo four years of additional training after medical school in women's health, pregnancy, delivery, and prenatal and postnatal care. The fallopian tubes carry eggs from the ovaries to the uterus, where fertilization can occur. Labor and delivery involves three stages - cervical dilation, birth of the baby, and expulsion of the placenta.