Umbilical cord blood is up to 180mL of blood from a newborn baby that is returned to the neonatal circulation if the umbilical cord is not prematurely clamped. In some obstetric and midwifery practices, physiological extended-delayed cord clamping protocol, as well as water birth, allows for the cord blood to pulse into the neonate for 5-20 minutes after delivery. If the umbilical cord is not clamped, a physiological clamping occurs upon interaction with cold air, when the internal gelatinous substance, called Wharton's jelly, swells around the umbilical artery and veins.

Cord blood harvesting

A cord blood bank may be a private commercial enterprise, or public medical resource, used to store umbilical cord blood for future use.

Cord blood banking is controversial in the medical and parenting community. Blood collected this way takes up to 180mL from the neonate (sometimes up to half of the total blood volume) which is a highly controversial subject in perinatal medicine. Cord blood is rich in hematopoietic stem cells, however, The American Academy of Pediatrics 2007 Policy Statement on Cord Blood Banking^[1] 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;"

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 supported by the medical community. However, private cord blood banking is generally not recommended unless there is a family history of specific genetic diseases.