This is true in part because bone marrow transplants require a more precise tissue match than do umbilical cord blood transplants.
Every newborn is a potential donor.
As a result, patients' needs and not donors' schedules dictate the timing of transplant. Better availability means cord blood transplants can be performed more quickly than bone marrow transplants once a virulent cancer is diagnosed. By contrast, bone marrow transplant patients may wait months for a suitable donor. In 25 percent of the cases, a bone marrow donor is not available when the patient needs the transplant. Even when a suitable bone marrow match is found, the donor may not be in a position to undergo the surgery that marrow-extraction requires.