Understanding Rh-Negative: What Does It Mean To Be Rh-Negative

Being Rh-negative means you don't have a certain protein ("D antigen" or the Rh factor) on the surface of your red blood cells. If you do have it, you're Rh-positive. So the terms "Rh-negative" and "Rh-positive" are really just terms that further define what type of blood a person has, beyond the general blood type categories of A, B, AB, and O.

Being Rh-negative is neither good nor bad, but it can become a serious issue if you're pregnant by or planning to have a child with a man who is Rh-positive.

In the United States, the population of Rh-negative individuals varies among ethnic groups. The highest prevalence is found among Caucasians (15%), followed by African Americans and Hispanics (8% each), and Asians and Native Americans (1% each). For the small percentage of people who are Rh-negative, their blood type causes no special health concerns except when they give or receive blood, or during pregnancy.


If you're Rh-negative and carrying a baby who is Rh-positive (like the baby's father), your baby may be at risk for a serious disease. When your immune system (which fights off invaders to keep you healthy) is exposed to your baby's Rh-positive blood, it will begin producing antibodies that are sensitized (designed specifically) to destroy these "foreign" blood cells.

If this is your first pregnancy, chances are everything will be fine. These sensitized antibodies are typically not dangerous until subsequent pregnancies, when they've had time to grow in strength and number. However, all subsequent pregnancies would be at great risk. That is why you must act now to prevent your immune system from being exposed to Rh-positive blood.


If your immune system is not held in check by a product such as RhoGAM® Brand, sensitized antibodies programmed to recognize and attack any Rh-positive blood cells are waiting for the next pregnancy. The antibodies then begin to destroy the red blood cells of the baby, leading to complications such as jaundice, anemia, mental retardation, and heart failure.1 This condition, known as hemolytic disease of the fetus and newborn (HDFN), can be fatal in the most severe cases-the infant would typically die during pregnancy or shortly after delivery.

Prior to the introduction of RhoGAM® Brand in 1968, HDFN was a major cause of infant mortality, responsible for an average of 10,000 deaths annually in the United States.2 Since the introduction of Rh immune globulin products, like RhoGAM® Brand, the incidence of HDFN has been virtually eliminated in most developed countries.


  1. Rubin E, Farber JL. Developmental and genetic diseases. In: Rubin E, Farber JL, eds. Pathology. 2nd ed. Philadelphia, PA: J.B. Lippincott Company; 1994:255-258.
  2. Zimmerman DA. Rh: The Initmate History of a Disease and its Conquest. New York, NJ: MacMilan Publishing Company. May 1973.

Important Safety Information

RhoGAM® Brand is indicated for the prevention of Rh immunization, including during and after pregnancy and other obstetrical conditions or incompatible transfusion of Rh-positive blood.

RhoGAM® and MICRhoGAM® Ultra-Filtered PLUS Rho(D) Immune Globulin (Human) are made from human plasma. Since all plasma-derived products are made from human blood, they may carry a risk of transmitting infectious agents, e.g., viruses, and theoretically the Creutzfeldt-Jakob disease (CJD) agent.


RhoGAM® and MICRhoGAM® contain a small quantity of IgA and physicians must weigh the benefit against the potential risks of hypersensitivity reactions. Patients who receive RhoGAM® and MICRhoGAM® for Rh-incompatible transfusion should be monitored by clinical and laboratory means due to the risk of a hemolytic reaction.

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