Hemolytic disease of the newborn

What is hemolytic disease of the newborn? 

Hemolytic disease of the newborn (HDN), also called erythroblastosis fetalis, is a blood disorder that occurs when the blood types of a mother and baby are incompatible. If the baby’s incompatible red blood cells cross over to his mother, through the placenta during pregnancy or at delivery, her immune system sees them as foreign and responds by developing proteins called antibodies to attack and break them down. This can lead to several complications that range from mild to very severe.

The mother’s immune system also keeps these antibodies in case the incompatible red blood cells appear again, making her “sensitized.” Because of this, HDN is more likely to occur during a mother’s second or subsequent pregnancy, or following a miscarriage or abortion.

Complications of hemolytic disease of the newborn during pregnancy:

• Mild anemia: When the baby’s red blood cell count is deficient, his blood cannot carry enough oxygen from the lungs to all parts of his body, causing his organs and tissues to struggle.
• Hyperbilirubinemia and jaundice: The breakdown of red blood cells produces bilirubin, a brownish yellow substance that is difficult for a baby to discharge and can build up in his blood (hyperbilirubinemia) and make his skin appear yellow.
• Severe anemia with enlargement of the liver and spleen: The baby’s body tries to compensate for the breakdown of red blood cells by making more of them very quickly in the liver and spleen, which causes the organs to get bigger. These new red blood cells are often immature and unable to function completely, leading to severe anemia.
• Hydrops fetalis: When the baby’s body cannot cope with the anemia, his heart begins to fail and large amounts of fluid build up in his tissues and organs.

Complications of hemolytic disease of the newborn after birth:

• Severe hyperbilirubinemia and jaundice: Excessive buildup of bilirubin in the baby’s blood causes his liver to become enlarged.
• Kernicterus: Buildup of bilirubin in the blood is so high that it spills over into the brain, which can lead to permanent brain damage.

What causes hemolytic disease of the newborn?

A person’s blood type is determined by the presence of two different types of proteins, called antigens. The A, B and O antigens represent the classification of a person’s blood as Type A, B, AB or O. If a person also has the Rh factor antigen, his blood is Rh -positive, and if not, it is Rh-negative.

Rh incompatibility:

Hemolytic disease of the newborn most frequently occurs when a mother with Rh-negative blood becomes pregnant by an Rh- positive father, resulting in an Rh-positive baby.

ABO incompatibility:

Although it is not as common, hemolytic disease of the newborn can also occur when a mother and baby have incompatible blood types, specifically:

Is hemolytic disease of the newborn common?

Hemolytic disease of the newborn (HDN) is relatively uncommon in the United States due to advances in early detection and treatment, limiting it to approximately 4,000 cases a year. It is more likely to happen during a mother’s second or subsequent pregnancy. HDN due to Rh incompatibility occurs more frequently and is about three times more likely in Caucasian babies than in African-American babies.

What are the symptoms of hemolytic disease of the newborn?
The most common symptoms of hemolytic disease of the newborn are:

• pale skin
• yellowing of the amniotic fluid, umbilical cord, skin and eyes
• enlarged liver or spleen
• severe swelling of the body

Can hemolytic disease of the newborn be prevented?

Hemolytic disease of the newborn is very preventable. Today, nearly all women with Rh-negative blood are identified in early pregnancy through blood tests. If a mother is Rh-negative and has not been sensitized, she is usually given a drug called Rh immunoglobulin, or RhoGAM. This specially developed blood product prevents an Rh-negative mother's antibodies from reacting to her baby’s Rh-positive red blood cells. Mothers are typically given RhoGAM around the 28th week of pregnancy and again within 72 hours of giving birth.