Hemolytic disease of the newborn

Hemolytic disease of the newborn (HDN) is a blood disorder in a fetus or newborn infant. In some infants, it can be fatal. Normally, red blood cells (RBCs) last for about 120 days in the body. In this disorder, RBCs in the blood are destroyed quickly and thus do not last as long.

The hemolytic condition occurs when there is an incompatibility between the blood types of the mother and fetus. There is also potential incompatibility if the mother is Rh negative and the father is positive. When any incompatibility is detected, the mother often receives an injection at 28 weeks gestation and at birth to avoid the development of antibodies towards the fetus. These terms do not indicate which specific antigen-antibody incompatibility is implicated. The disorder in the fetus due to Rh D incompatibility is known as erythroblastosis fetalis.

Hemolytic comes from two words: “hema” (blood) and “lysis” (solution) or breaking down of red blood cells
Erythroblastosis refers to the making of immature red blood cells
Fetalis refers to the fetus.

When the condition is caused by the Rh D antigen-antibody incompatibility, it is called Rh D Hemolytic disease of the newborn or Rh disease. Here, sensitization to Rh D antigens (usually by feto-maternal transfusion during pregnancy) may lead to the production of maternal IgG anti-D antibodies which can pass through the placenta. This is of particular importance to D negative females at or below childbearing age, because any subsequent pregnancy may be affected by the Rh D hemolytic disease of the newborn if the baby is D positive. The vast majority of Rh disease is preventable in modern antenatal care by injections of IgG anti-D antibodies (Rho(D) Immune Globulin). The incidence of Rh disease is mathematically related to the frequency of D negative individuals in a population, so Rh disease is rare in old-stock populations of Africa and the eastern half of Asia, and the Indigenous peoples of Oceania and the Americas, but more common in other genetic groups, most especially Western Europeans, but also other West Eurasians, and to a lesser degree, native Siberians, as well as those of mixed-race with a significant or dominant descent from those (e.g. the vast majority of Latin Americans and Central Asians).

Symptoms and signs in the fetus:

Enlarged liver, spleen, or heart and fluid buildup in the fetus’ abdomen seen via ultrasound.

Symptoms and signs in the newborn:

Anemia that creates the newborn’s pallor (pale appearance).
Jaundice or yellow discoloration of the newborn’s skin, sclera or mucous membrane.
This may be evident right after birth or after 24–48 hours after birth.
This is caused by bilirubin (one of the end products of red blood cell destruction).
Enlargement of the newborn’s liver and spleen.
The newborn may have severe edema of the entire body.
Dyspnea (difficulty breathing)

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Hemolytic disease of the newborn