Cord blood banks are institutions designed to store umbilical cord blood (UCB) stem cells. UCB, a source of hematopoietic stem cells (HSCs), has garnered attention from scientific and medical communities since its first successful use in a hematopoietic stem cell transplant (HSCT) in 1988. The umbilical cord is the lifeline by which the growing fetus is nourished by the mother. Once regarded as medical waste, the umbilical cord has become a source of lifesaving treatment. The extraction of HSCs from umbilical cord is non-invasive since the umbilical cord is delivered immediately after the baby exits the womb. The most common application of umbilical cord blood derived stem cells is in unrelated (between donor and host) HSCT. Since these cells are not often needed at the time of delivery, cord blood banks have been established to preserve these cells for future use. In addition to harvesting a supply of cells for treatment, UCB stem cells can be used in research.

Rh factor is a protein found on the outside of Rh-positive red blood cells. Rh incompatibility during pregnancy occurs when an Rh-negative mother is pregnant with an Rh-positive fetus. During delivery, the fetus' Rh-positive blood is introduced into the mother’s body. The Rh-negative mother’s body begins to produce antibodies that attack and kill Rh-positive blood cells. Since the crossover of blood normally occurs during delivery, an Rh-negative woman’s first pregnancy is normally not affected.