Fetal blood or fetal hemoglobin is the blood within a fetus or newborn baby. This blood usually stays in circulation until its gradual replacement by the time the baby is six months old. Fetal blood has properties that suit a fetus and infant’s specific needs.
The fetus acquires all its necessary oxygen and nutrients from the mother’s blood. The fetal blood is most efficient at processing oxygen, it is actually much better than the most developed adult respiratory system. Fetal blood contains 50% more hemoglobin than normal blood meaning that the fetus has more proteins that help it to circulate the oxygen in the blood. These higher levels of hemoglobin allow it to carry between 20 and 30% more oxygen than normal blood. Fetal blood reaches the fetus through the umbilical vein in the umbilical cord which carries blood rich oxygen from the placenta.
At birth, a drastic reduction in fetal blood occurs as the baby is no longer attached to the placenta through the umbilical cord. Fetal blood decreases to about 50% and continues to lower and by 6 months, a normal baby will no longer have fetal blood. However, sometimes this takes too long to happen or might never happen causing illness in the child and adult who has such a condition. This is an inherited condition called hereditary persistence of fetal hemoglobin (HPFH). Sickle cell anemia occurs when fetal blood is replaced by hemoglobin S instead of normal hemoglobin, it is treated by increasing fetal blood in circulation.