There are several advantages of transplanting stem cells from cord blood instead of from bone marrow. There is also two disadvantages to doing so.

Here are the advantages:

1. Harvesting umbilical blood poses no risk to either mother or child. Conversely, a bone marrow donor must undergo anesthesia and is exposed to the risk of infection.

2. Umbilical blood can be stored in cryogenic freezers, ready for use as soon as it is needed, whereas the process of contacting and testing donors listed in a bone marrow registry takes weeks to months.
Umbilical blood units are stored and ready to use. It can take two months or more to find an unrelated bone marrow donor. An umbilical blood unit can be selected and delivered to the transplant center in less than a week. Your doctor may choose cord blood if you need a transplant quickly. This factor alone makes umbilical blood banking much more appealing.

3. The stem cells in umbilical blood are more primitive than those in bone marrow. As such, they carry much lower incidence of graft versus host disease (GVHD). Thus, cord blood transplants do not require a "perfect match" between the donor and the patient.
Graft-versus-host disease (GVHD) is a common complication after an allogeneic transplant. GVHD can range from mild to life-threatening. Studies have found that after a cord blood transplant, fewer patients get GVHD than after bone marrow transplants. Patients in the studies who did get GVHD after a cord blood transplant tended to get less severe cases.

4. A close match between the patient and the donor or umbilical blood unit can improve a patient's outcome after transplant. Even though a closely matched cord blood unit is preferred, clinical studies suggest the match do not have to be as close as is needed for bone marrow transplants. If you have an uncommon tissue type, your doctor may not find a closely matched adult bone marrow donor for you. However, a cord blood unit may be an option.

Here are the disadvantages of transplanting with umbilical blood:

1. The stem cells in cord blood are more primitive than those in bone marrow, and because of this the engraftment process takes longer with cord blood. During this time, the patient is vulnerable to infection for a longer period.

2. A typical umbilical blood harvest only contains enough stem cells to transplant a large child or small adult (weighing approx. 100 pounds). Researchers are developing methods of transplanting adults with cord blood, and this may not be a factor in the near future. When this process is common, cord blood banking will likely become standard procedure after birth.