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What Is RH Negative Blood?

Negative blood types are missing the Rhesus (Rh) factor, an antigen found on the surface of red blood cells. Negative blood types are rare and found in only 15 percent of the world's population.

  1. Discovery of Blood Types

    • The ABO blood group system was discovered in 1901 by biologist Karl Landsteiner at the University of Vienna; he also discovered the Rh factor alongside Dr. Alexander S. Wiener in 1937. These achievements greatly improved the quality and efficacy of blood transfusions.

    Compatibility

    • Rh- blood types are compatible with at least one other negative type, except O- which, despite being a universal donor, cannot receive any other type. AB- can receive all negative blood types.

    Prevalence by Race

    • The highest concentration of Rh- blood types are found in the Basque people of Europe at approximately 35 percent. Europeans altogether carry a rate of 16 percent, followed by African Americans at 5 to 10 percent.

    Rh Incompatibility in Pregnancy

    • Rh incompatibility occurs when an Rh- woman becomes pregnant with an Rh+ baby. If the baby's Rh+ blood is introduced into the mother's bloodstream her body reacts by producing antibodies to combat the foreign blood cells. The first baby is usually unharmed, but a second Rh+ pregnancy places the fetus at high risk of hemolytic disease.

    Treatment

    • Fortunately, an Rh immune globulin injection can help prevent Rh- mothers from developing antibodies. The injection is usually taken in the 28th week of pregnancy and again after delivery.

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