 The blood in an unborn babys umbilical cord contains blood-making cells that could help treat another person with a life-threatening disease. These cord blood cells may provide cells for transplants given to patients with marrow diseases such as leukemia. These cord blood transplants can be done when a patients cell type human leukocyte antigen, or HLA, type matches the cord blood type. Cord blood is normally thrown away with the umbilical cord and placenta after the baby is born. 