This disorder may result from postmaturity, diabetes in the mother, twin-to-twin transfusions, in which blood flows from one fetus to the other, or a low oxygen level in the fetus's blood.
A high concentration of red blood cells makes the blood thick (hyperviscosity) and may slow blood flow through small blood vessels.
Most affected newborns do not have symptoms but occasionally have a ruddy or dusky color, are sluggish (lethargic), feed poorly, and very rarely have seizures.
The diagnosis is based on a test that measures the amount of red blood cells in the blood.
Usually no treatment is needed except to give fluids.
When the newborn has symptoms, treatment with a partial exchange transfusion may be given to reduce the concentration of red blood cells.
Red blood cells contain hemoglobin, a protein that gives blood its red color and enables it to carry oxygen from the lungs and deliver it to all body tissues. Oxygen is used by cells to produce energy that the body needs, leaving carbon dioxide as a waste product. Red blood cells carry carbon dioxide away from the tissues and back to the lungs.
A markedly increased concentration of red blood cells may cause the blood to be too thick. Blood that is too thick slows the flow of blood through small blood vessels and interferes with the delivery of oxygen to tissues. A newborn who is born postterm or whose mother has diabetes, has severe high blood pressure, smokes, or lives at a high altitude is more likely to have polycythemia.
Polycythemia may also result if the newborn receives too much blood from the placenta (the organ that connects the fetus to the uterus and provides nourishment to the fetus) at birth, which may occur if the newborn is held below the level of the placenta for too long before the umbilical cord is clamped.
Other causes of polycythemia include a low oxygen level in the blood (hypoxia), perinatal asphyxia, growth restriction in the womb, birth defects (such as some heart problems or kidney problems), Down syndrome, Beckwith-Wiedemann syndrome, or a large transfusion of blood from one twin to another (twin-to-twin transfusion).
A newborn with severe polycythemia has a very ruddy or dusky color, is lethargic, feeds poorly, and may have seizures.
If the newborn has no symptoms, fluids for hydration are given by vein because dehydration (fluid loss) can make the blood even thicker.
If the newborn has symptoms, some of the newborn’s blood is removed and replaced with an equal amount of saline solution. This procedure, called partial exchange transfusion, dilutes the remaining red blood cells and corrects the polycythemia.