Hemolytic disease of the newborn

  • Definition
    • Hemolytic disease of the newborn (HDN) is a blood disorder in a fetus or newborn infant. In some infants, it can be life threatening.

      Normally, red blood cells last for about 120 days in the body. In this disorder, red blood cells in the blood are destroyed earlier than normal.

  • Alternative Names
    • Hemolytic disease of the fetus and newborn (HDFN); Erythroblastosis fetalis; Anemia - HDN; Blood incompatibility - HDN; ABO incompatibility - HDN; Rh incompatibility - HDN

  • Causes
    • During pregnancy, red blood cells from the unborn baby can cross into the mother's blood through the placenta. HDN occurs when the immune system of the mother sees a baby's red blood cells as foreign. Antibodies then develop against the baby's red blood cells. These antibodies attack the red blood cells in the baby's blood and cause them to break down too early.

      HDN may develop when a mother and her unborn baby have different blood types. The types are based on small substances (molecules) on the surface of the blood cells.

      There are 2 ways that the unborn baby's and the mother's blood may not match.

      • A, B, AB, and O are the 4 major blood types. This is the most common form of a mismatch. In most cases, this is not very severe.
      • If the mother is Rh-negative and the baby in the womb has Rh-positive cells. When this form does occur, it can cause very severe anemia in the baby. It can be prevented in most cases.
  • Symptoms
    • HDN can destroy the newborn baby's blood cells very quickly, which can cause symptoms such as:

      • Edema (swelling under the surface of the skin)
      • Newborn jaundice which occurs sooner and is more severe than normal
  • Exams and Tests
    • Signs of HDN include:

      • Anemia or low blood count
      • Enlarged liver or spleen
      • Hydrops (fluid throughout the body's tissues, including in the spaces containing the lungs, heart, and abdominal organs), which can lead to heart failure and/or respiratory failure from too much fluid

      Which tests are done depends on the type of blood group incompatibility and the severity of symptoms, but may include:

  • Treatment
    • Infants with HDN may be treated with:

      • Feeding often and receiving extra fluids
      • Light therapy (phototherapy) using special blue lights to convert bilirubin into a form in which the baby's body can get rid of it
      • Antibodies (intravenous immunoglobulin, or IVIG) to help protect the baby's red cells from being destroyed
      • Medicines to raise blood pressure if it drops too low
      • In severe cases, an exchange transfusion may need to be performed. This involves removing a large amount of the baby's blood, and thus the extra bilirubin and antibodies. Fresh donor blood is infused.
  • Outlook (Prognosis)
    • The severity of this condition can vary. Some babies have no symptoms. In other cases, problems such as hydrops can cause the baby to die before, or shortly after birth. Severe HDN may be treated before birth by intrauterine blood transfusion.

  • Prevention
    • The most severe form of this disease, which is caused by Rh incompatibility, can be prevented if the mother if the mother is tested during pregnancy. If needed, she is given a shot of a medicine called RhoGAM at certain times during and after her pregnancy. If you have had a baby with this disease, talk with your health care provider if you plan to have another baby.

  • References
    • Dahlke JD and Magann EF. Immune and non-immune hydrops fetalis. In: Martin RJ, Fanaroff AA, Walsh MC, eds. Fanaroff and Martin's Neonatal-Perinatal Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 24.

      Maheshwari A, Carlo WA. Blood disorders. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 103.