What Is RhoGAM?

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RhoGAM is one brand of Rh immunoglobulin (RhIg). RhIg is an injectable drug given to pregnant people with Rh-negative blood during pregnancy.

Every person is born with a blood type—O, A, B, or AB and a Rhesus (Rh) factor, which is positive or negative. A simple blood test can determine your blood type and Rh status. This test usually happens during your first prenatal care visit.

When you're Rh-negative and the baby’s biological father is Rh-positive, some life-threatening complications can arise if the baby inherits the dad’s positive Rh factor. This is called Rh incompatibility, or Rh disease. The main purpose of RhoGAM is to prevent Rh incompatibility.

While the term “Rh incompatibility” may sound serious, treatment is simple and low-risk. Here’s what to expect if you need a RhoGAM injection.

Doctor holding medication in the syringe, preparing for injection for a pregnant woman during a medical procedure in the clinic, close-up view

RossHelen / Getty Images

What Is Rh Factor?

The Rh factor is a protein that can be found on the surface of red blood cells. If you have this protein, you're Rh-positive. If you don’t, you're Rh-negative. Just 18% of the U.S. population has an Rh-negative blood type.

Concerns come up during pregnancy when negative and positive blood has the potential of mixing.

Importance of RhoGAM

While the pregnant person and fetus's blood systems are separate, there are times when the blood from the fetus can enter the mother's bloodstream. If the pregnant person is Rh-negative, their immune system treats Rh-positive fetal cells as an attack and responds by making antibodies to destroy them. This response is called Rh sensitization.

The antibodies in an Rh-sensitized pregnant person can cross the placenta and attack the fetus's Rh-positive blood. These antibodies can break down and destroy the fetus's red blood cells (hemolysis), leading to anemia. This condition is called hemolytic disease or hemolytic anemia.

RhoGAM stops your blood from making antibodies that kill Rh‐positive blood cells. The drug is derived from donated human plasma (a blood product) and has a very small amount of Rh‐positive protein that stops your body from making permanent antibodies against Rh‐positive blood.

Is RhogGAM Safe for My Baby?

RhoGAM does not hurt you or your baby.

If a pregnant person’s blood is sensitized to Rh factor, the sensitization may be permanent and they risks delivering anti-Rh antibodies to their future babies. Once Rh sensitization happens, all future pregnancies with an Rh‐positive baby are at high risk for the baby being very sick.

When Is RhoGAM Given?

An Rh-negative pregnant person will receive RhoGAM at several points throughout pregnancy when the Rh factor of the biological father is positive or unknown.

RhoGAM is routinely given whenever there’s a possibility of your blood mixing with the baby's blood. These include:

  • At 26 to 28 weeks of pregnancy, when the placenta can start to thin and, although unlikely, blood can transfer from baby to pregnant person
  • Within 72 hours of delivery, including cesarean delivery, if the baby is Rh-positive
  • After any invasive testing of the baby’s cells, for example, during:
    amniocentesis, a test that examines amniotic fluid for developmental abnormalities
  • Chorionic villus sampling (CVS), a test that looks at tissue samples for genetic problems

A dose of RhoGAM also may be needed:

At any time during your pregnancy, notify your healthcare provider immediately if you have vaginal bleeding or experience any abdominal trauma. You may need an additional dose of RhoGAM.

How Do I Know If My Baby Is Rh-Positive?

Soon after you give birth, your baby's blood will be tested for the blood type and Rh type. If your baby has Rh‐positive blood, you will get another shot of RhoGAM within 72 hours after you give birth. If your baby's blood is Rh-negative, you will not need the second RhoGAM shot.

Common Side Effects of RhoGAM

All medications carry the risk of some side effects. The most common adverse reactions of RhoGAM include:

  • Injection site reactions (pain discomfort, or tenderness)
  • Fever
  • Joint or muscle pain
  • Headache
  • Dizziness
  • Tiredness
  • Itching
  • Nausea
  • Diarrhea
  • Vomiting
  • Stomach pain

Allergic Reactions to RhoGAM

Allergic reactions to RhoGAM may occur. You should be observed for at least 20 minutes after your injection. Signs and symptoms of an allergic reaction include:

  • Itchy rash
  • Tightness of the chest
  • Tongue swelling
  • Shortness of breath
  • Wheezing
  • Low blood pressure

RhoGAM Safety

The RhoGAM shot is safe, has been used since the late 1960s, and is recommended for all pregnant people who have Rh‐negative blood.

If you're worried about getting the RhoGAM injection because it is made from donated human plasma, keep in mind there's minimal to no risk of contracting diseases like HIV or hepatitis because the donated plasma is thoroughly screened and treated.

Rh disease doesn’t affect your health—but if you decline the RhoGAM shot, it can impact the health of your baby and those of future pregnancies. In factone in five Rh-negative pregnant people will become sensitive to the Rh-positive factor if they don't receive RhoGAM.

There is a very rare chance that you will have an allergic reaction to the RhoGAM, but the chance of developing Rh sensitization is much higher than the risk of problems from the RhoGAM shot.

Who Should Not Get a RhoGAM Shot?

RhoGAM should not be used if you are Rh-positive or if you have had a severe allergic reaction to human immune globulin.

Be sure to tell your healthcare provider about all your medical conditions, including:

  • If you have an immunoglobulin A (IgA) deficiency. RhoGAM contains a small quantity of IgA and there is a potential risk of an allergic reaction in IgA-deficient individuals. Ask your healthcare provider if you are not sure.
  • If you have hemolytic anemia.
  • Your vaccine history—RhoGAM may interfere with the response to live virus vaccines (e.g., measles, mumps, rubella, and varicella). Before you get a vaccine, tell your healthcare provider that you have received RhoGAM.

RhoGAM and COVID-19 Vaccine

As per guidance from the Centers for Disease Control and Prevention (CDC) and the American College of Obstetricians and Gynecologists (ACOG), RhoGAM should not be withheld from an individual who is planning or has recently received a COVID-19 vaccine as it will not interfere with the immune response to the vaccine.


RhoGAM is an injectable drug given to pregnant people with Rh-negative blood during pregnancy. It is generally safe, but if you're concerned, speak with your healthcare provider.

A Word From Verywell

Finding out that you and your baby may be Rh incompatible can be worrying. But know that the RhoGAM shot is a safe and effective way to prevent potential problems—both now and for future pregnancies. 

If you think you may be pregnant and have an Rh-negative blood type, you should talk with your healthcare provider to determine the best plan. If the father of your child is Rh-positive or his blood type is unknown, receiving preventive treatment with RhoGAM will prevent serious effects.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  3. National Heart, Lung, and Blood Institute. Rh incompatibility.

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  5. MedlinePlus. Rh incompatibility.

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