Answers to your Frequently Asked Questions

What does it mean to be Rh-negative?

People are either Rh-positive or Rh-negative. Rh-positive people have an Rh antigen (also called Rhesus factor or D antigen) on the surface of their red blood cells. Rh-negative people do not have this antigen. The Rh (D antigen) factor is inherited, like eye color, and some people simply do not receive it from their parents. The prevalence of Rh-negative women in a given geographic area varies by race. The table below shows the U.S. frequency figures.

Frequency of Being Rh-negative by Race (U.S.)1
Race Rh-Positive Rh-Negative
Caucasian 85% 15%
African American 92% 8%
Hispanic 92% 8%
Native American 99% 1%
Asian 99% 1%

What does “Rh” stand for?

Rh is the abbreviation for Rhesus, the name of one of many different blood group systems in the body. Within the Rhesus system, there are 33 different antigens or Rh factors. The first of these factors is the “D” antigen, also referred to as Rho(D). It is the presence or absence of the D antigen on your red blood cells that determines whether you’re Rh-positive or Rh-negative.

Why do I need RhoGAM® Ultra-Filtered PLUS?

Because your blood is Rh-negative, your doctor is advising you to receive an injection of an anti-D product such as RhoGAM® Brand Ultra-Filtered PLUS Rho(D) Immune Globulin (Human), manufactured by Ortho Clinical Diagnostics for Kedrion Biopharma. This means that you do not have a factor called the “D antigen” on your red blood cells. When an Rh-negative woman becomes pregnant, RhoGAM® Brand Ultra-Filtered PLUS can help prevent problems that might arise if her blood is incompatible with her baby’s blood (which may be Rh-positive).

What kind of problems might I have during pregnancy because I’m Rh-negative?

When an Rh-negative woman carries an Rh-positive baby, small numbers of the baby’s red blood cells may get into the mother’s bloodstream. This can happen during her pregnancy as well as at delivery. The mother’s immune system sees the baby’s Rh-positive red blood cells as foreign and goes to work to produce antibodies against them. Once the expectant mom is sensitized, meaning she has developed anti-D antibodies, administering an Rh immune globulin product is not effective. A simple blood test will determine if the Rh-negative expectant mom is already sensitized. Your doctor will monitor your pregnancy to see if the fetus is harmed as symptoms of sensitization may vary.

Can the antibodies my immune system produce hurt my baby?

Yes. The antibodies formed to protect you against Rh-positive red blood cells can pass to the baby you are carrying. They attack and destroy the baby’s Rh-positive red blood cells, causing anemia (low red blood cell count), jaundice, and in severe cases, heart failure. This condition is known as hemolytic disease of fetus and newborn, or HDFN.

Is every Rh-positive baby carried by an Rh-negative mother at risk for HDFN?

HDFN usually does not affect the mother’s first baby, but once she has produced Rh antibodies, all future Rh-positive babies are at risk for HDFN.

What if my baby has inherited my Rh-negative blood?

Before birth, the baby’s Rh blood type can only be determined through invasive procedures (like amniocentesis). It is safer to assume that the baby is Rh-positive and administer RhoGAM® Ultra-Filtered PLUS during pregnancy. If your baby is determined to be Rh-negative at birth, you do not need an additional dose of RhoGAM® Brand.

How does RhoGAM® Ultra-Filtered PLUS work?

RhoGAM® Ultra-Filtered PLUS is a sterile solution that contains antibodies to the Rh factor. The antibodies are derived from human plasma. When RhoGAM® Brand is injected into the muscle of an Rh-negative mother, these antibodies circulate in her bloodstream and protect her against any Rh-positive red blood cells from the fetus. Her immune system then sees no need to take further action.

Will my unborn baby be harmed by the RhoGAM® Ultra-Filtered PLUS antibodies?

No. The small amount of antibody in RhoGAM® Brand has never been shown to harm the fetus. Millions of doses have been administered safely to Rh-negative mothers who have delivered healthy babies. Additionally, RhoGAM® Brand does not contain preservatives.

When will I receive RhoGAM® Ultra-Filtered PLUS?

An Rh-negative mother is most likely to be exposed to her baby’s blood during the last three months of pregnancy and at delivery. Therefore, your doctor will likely prescribe at least one dose of RhoGAM® Ultra-Filtered PLUS at around 28 weeks of pregnancy, and a second dose will be given for added protection within 72 hours after delivery if the baby is found to be Rh-positive. You should also receive RhoGAM® Brand after abdominal trauma or immediately after an invasive procedure is performed (such as amniocentesis) and then every 12 weeks thereafter.

Will I need RhoGAM® Ultra-Filtered PLUS during and after each pregnancy?

Yes, because every pregnancy puts the Rh-negative mother at risk of being exposed to the Rh-positive red blood cells of her baby.

Is RhoGAM® Ultra-Filtered PLUS necessary after an induced pregnancy termination?

Yes. The Rh factor is present on the red blood cells from the time the fetus is eight weeks old. If a spontaneous or induced pregnancy termination occurs at or beyond 13 weeks of pregnancy, a full dose of RhoGAM® Ultra-Filtered PLUS should be administered. Before 13 weeks, a smaller dose, MICRhoGAM® Ultra-Filtered PLUS, may be given.

Does RhoGAM® Ultra-Filtered PLUS have side effects?

Side effects of RhoGAM® Brand are rare and extremely mild. You may feel soreness, tenderness, and warmth or develop a rash at the site of injection. Other mild side effects may include fever, chills, headache, or a feeling of fatigue. If you experience other symptoms, please call your doctor. Contact your doctor if you have any questions about RhoGAM® Ultra-Filtered PLUS and your pregnancy.


  1. Reid ME, Lomas-Francis C. The Blood Group Antigen Facts Book. New York, NY: Academic Press, 1997.

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® are intended for maternal administration. Do not inject the newborn infant. Local adverse reactions may include redness, swelling, and mild pain at the site of injection and a small number of patients have noted a slight elevation in temperature. Patients should be observed for at least 20 minutes after administration. Hypersensitivity reactions include hives, generalized urticaria, tightness of the chest, wheezing, hypotension and anaphylaxis.

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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