Umbilical cord blood is blood from a newborn baby, collected from its placenta and umbilical cord after the cord has been clamped. Blood collected this way at birth is utilized as a source of stem cells for transplantation, being rich in hematopoietic stem cells.

Cord blood is stored by both public and private cord blood banks. Public cord blood banks store cord blood for the benefit of the general public, and most U.S. banks coordinate matching cord blood to patients through the National Marrow Donor Program (NMDP). Private cord blood banks are for-profit organizations which store cord blood for the exclusive use of the donor or donor's relatives.

Public cord blood banking is strongly supported by the medical community. However, private cord blood banking is generally not recommended unless there is a family history of specific genetic diseases. Private banking is unlawful in France and Italy, and opposed by the European Group on Ethics in Science and New Technologies.

Cord blood harvesting is a controversial practice in the medical and parenting community. The American Academy of Pediatrics 2007 Policy Statement on Cord Blood Banking states that:

"Physicians should be aware of the unsubstantiated claims of private cord blood banks made to future parents that promise to insure infants or family members against serious illnesses in the future by use of the stem cells contained in cord blood;"

Properties

Stem cells from the blood of newborns are more proliferate and have a higher chance of matching family members than stem cells from bone marrow. Parents and siblings match 50% of the genetic markers of the donor's stem cell. However, since many different genetic markers are required for a match, the probability of a potential implant in a parent or sibling is considerably lower.

 Collection, storage and costs

Main article: Cord blood bank

Additional stem cells may be collected from the placenta via Placenta Cord Banking. After the health care provider draws the cord blood from the umbilical cord, the placenta is couriered to the stem cell laboratory where it is processed for additional stem cells. By banking stem cells derived from the placenta as well as umbilical cord blood, families may save more CD34+ stem cells for use in transplants. Having as many of these stem cells as possible is medically important: published research shows that the size of the stem cell transplant (especially the number of CD34+ cells) is consistently a significant factor in achieving a successful treatment and patient survival.

There are two methods of cord blood collection from the umbilical vein: before the placenta is delivered (in utero), and after (ex utero)

With the ex utero collection method, the cord blood is collected after the placenta is delivered and the umbilical cord is clamped off from the newborn. The placenta is placed in a sterile supporting structure with the umbilical cord hanging through the support. The blood is collected by gravity drainage yielding 40-150 mL of cord blood.

A similar collection method is performed in utero, except that the cord blood is collected after the baby has been delivered but before the delivery of the placenta.

After collection, the cord blood units must be immediately shipped to a cord blood bank facility. At public cord blood banks, this blood is then analyzed for infectious agents and the tissue type is determined. Cord blood is processed and depleted of red blood cells before being stored in liquid nitrogen for later use.

New parents have the option of storing their newborn's cord blood at a private cord blood bank or donating it to a public cord blood bank. The cost of private cord blood banking is approximately $2000 for collection and approximately $125 per year for storage, as of 2007. Donation to a public cord blood bank is not possible everywhere, but availability is increasing. Several local cord blood banks across the United States are now accepting donations from within their own states. The cord blood bank will not charge the donor for the donation; the OB/GYN may still charge a collection fee, although many OB/GYNs choose to donate their time.

After the first sibling-donor cord blood transplant was performed in 1988, the National Institute of Health (NIH) awarded a grant to Dr. Pablo Rubinstein to develop the world's first cord blood program at the New York Blood Center(NYBC), in order to establish the inventory of non embryonal stem cell units necessary to provide unrelated, matched grafts for patients.

In 2005, University of Toronto researcher Peter Zandstra developed a method to increase the yield of cord blood stem cells to enable their use in treating adults as well as children