Updates from Sierra Nevada Memorial Hospital and Hospital Foundation | TheUnion.com

Updates from Sierra Nevada Memorial Hospital and Hospital Foundation


In 1937, Karl Landsteiner and Alexander Weiner discovered a new blood type called the rhesus blood type or RH-factor. Named for the rhesus monkey which also carries the gene, it is a protein that lives on the surface of red blood cells. Landsteiner and Weiner discovered that blood types can be either Rh-positive or Rh-negative which doubled the blood types of A, B, AB and O to the eight we know today.

In the U.S., approximately 85% of the population has Rh-positive blood leaving only 15% with Rh-negative. The only way for someone to have a negative blood type is for parents to have at least one negative factor. If both parents have a positive Rh factor, it is impossible for their child to have a negative blood type

The RH protein was discovered as Landsteiner and Weiner were researching the cause of a medical mystery killing dozens of babies each day. This led to FDA (Food and Drug Administration) approval of RhoGAM in 1968.

RhoGAM is a prescription medicine that is administered by intramuscular injection. When a woman receives RhoGAM, it protects her immune system from exposure of the current baby’s Rh-positive blood. Pregnant women generally receive two doses of RhoGAM, once around 28 weeks, and once within 72 hours of delivery if in fact the newborn is Rh-positive.

Having an Rh-negative blood type can affect a pregnancy and may need special care. A health care provider will recommend an Rh screening test during a prenatal visit which is done with a blood test. Risk during pregnancy can occur if a small amount of the baby’s blood comes in contact with the mother’s blood during delivery or if there is bleeding or abdominal trauma.

If the mother is Rh-negative and the baby is Rh-positive, the body may produce proteins called Rh-antibodies after exposure to the baby’s red blood cells. These antibodies are not a concern during the first pregnancy. However, during the next pregnancy, if the baby is Rh-positive, these antibodies can cross the placenta and damage the baby’s red blood cells. Red blood cells are needed to carry oxygen throughout the body.

RH incompatibility does not affect pregnant women. For the baby, it can result in hemolytic anemia which results when the baby’s red blood cells are destroyed faster than they can be replaced. The effect of hemolytic anemia range from mild to severe.

Effects can include jaundice, liver failure and heart failure. Mild cases generally don’t need treatment. Severe cases are often treated by giving the baby a blood transfusion through the umbilical cord. Those with jaundice or large amounts of bilirubin in the blood are treated with special lights.

While people are accustomed to adding a positive or negative to their blood type, the Rh factor plays a more important role that most of us realize. Knowing your blood type can have a significant impact on your health and life.

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