http://www.nationalcordbloodprogram.org/qa/what_is_cordblood.html
After a baby is born and the umbilical cord is cut, some blood remains in the blood vessels of the placenta and the portion of the umbilical cord that remains attached to it. This blood is called placental blood or umbilical cord blood: "cord blood" for short. Find additional information about cord blood and its benefits, at this page.