Do I Really Need a RhoGAM Shot During Pregnancy?

If you’re currently pregnant, you may have heard that you might need a RhoGAM shot. But you may have many questions about the RhoGAM shot and whether it’s actually necessary. 

As one of the first decisions you need to make for your baby, you want to make sure you’re doing the right thing. Here’s what you should know about RhoGAM and its potential harms and benefits, so you can make the right choice for you and your baby.

What is RhoGAM?

RhoGAM is a medication that contains Rh immune globulin. RhoGAM is the brand name of this medication. There are other brand names and even a generic Rh immune globulin. But RhoGAM has become synonymous with Rh immune globulin, similar to how “Band-Aid” is synonymous for all bandages or “Kleenex” is used to refer to tissues.

Like all immunoglobulins, RhoGAM is an antibody. And like all antibodies, RhoGAM works by neutralizing something that can cause harm to our bodies. In this case, that harm is anti-D antibodies. 

RhoGAM is made from donated blood. When people donate their blood, the different cells are separated and combined with other people’s donated blood to make blood products. When we think of blood donors, we often only think of blood transfusions. But blood donors make all sorts of treatments possible, including immunoglobulin therapies. 

What is the Rh factor?

The Rh factor is a protein that’s found on the surface of red blood cells. There are many proteins on the surface of red blood cells. But not everybody has the Rh factor.

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Most people are familiar with AB antigens and the Rh factor, even if they don’t realize it. AB antigens determine a person’s blood type. The Rh factor determines whether a person has a negative or positive blood type. 

People who have the Rh factor on their red blood cells have a “positive” blood type (Rh-positive), including: 

• A+

• B+

• O+ 

• AB+

People who don’t have the Rh factor on their red blood cells have a “negative” blood type (Rh-negative), including:

• A -

• B -

• O - 

• AB -

Only 15% of people are Rh-negative. Your Rh factor doesn’t matter much in your day-to-day life, and it doesn’t affect your health. The only time your Rh factor matters is if you need a blood transfusion or if you’re pregnant.

People with a negative blood type can form anti-D antibodies if they’re exposed to a positive blood type (this usually only happens when someone is pregnant). Anti-D antibodies attack red blood cells that have the Rh factor on them. 

In short, if you’re Rh-negative and you’re pregnant, you can develop antibodies that attack your baby’s red blood cells. This can lead to serious health issues for an unborn baby.

When is RhoGAM given?

If you are Rh-negative, you will probably need a RhoGAM shot around your 28th week of pregnancy. You may also need a second dose after you deliver your baby. 

The RhoGAM shot stops your body from making anti-D antibodies that can attack your unborn baby’s red blood cells. This process is called Rh isoimmunization and can cause serious health problems in babies. 

Classic studies show that people who are Rh-negative have about a 1 in 5 chance of developing Rh isoimmunization. But with RhoGAM, that chance drops to almost zero.

People who are pregnant and Rh-negative might also need a RhoGAM shot if they have:

• An invasive procedure during pregnancy like an operation or an amniocentesis 

• Any trauma to the abdomen area during pregnancy, like being in a car accident

• An abortion, miscarriage, or fetal loss that happens after the 8th week of pregnancy

• Bleeding during pregnancy

• Manual attempts to change a baby from the breech position

When is it too late to get a RhoGAM shot?

If you’re pregnant and are Rh-negative, it’s never too late to get your RhoGAM shot. 

But it’s best to get your RhoGAM shot between 28 and 32 weeks so that the medication has a chance to work before you go into labor. 

If you need a RhoGAM shot after your delivery or because you had a procedure, a miscarriage, or an accident, you must receive your shot within 72 hours. Otherwise, the medication may not work.

When to get RhoGAM shot during a second pregnancy?

The timing of your RhoGAM shot stays the same no matter what pregnancy you’re in. You should receive your shot around your 28th week of pregnancy or sooner if you have any procedures or bleeding.

If you have a negative blood type, you need a RhoGAM shot during every pregnancy. In fact, it’s even more important to get the shot during subsequent pregnancies. That’s because if you had a baby with a Rh-positive blood type, you were exposed to your baby’s Rh-positive blood during your delivery.

Why do only Rh-negative people need a RhoGAM shot during pregnancy?

If you are Rh-negative and your baby is Rh-positive, you can develop antibodies against your baby’s blood. This is called Rh isoimmunization.

Rh isoimmunization only happens if you are Rh-negative and your baby is Rh-positive. If you are Rh-positive, this reaction doesn’t happen, regardless of whether your baby is Rh-positive or -negative. The reaction also doesn’t happen if you and your baby are both Rh-negative. 

When you’re pregnant, some of your baby’s blood crosses over the placenta and into your bloodstream. If you are Rh-negative and your baby is Rh-positive, your immune system will make antibodies when it comes in contact with your baby’s blood. The more of your baby’s blood that crosses over, the more antibodies your body will make.

Your antibodies can then cross the placenta and attack your baby’s red blood cells. When this happens, your baby can develop anemia. While many babies only develop mild anemia, others can have severe anemia. This can lead to multiple complications during pregnancy or after birth. 

The RhoGAM shot stops your body from creating these antibodies, which keeps your baby safe. Before RhoGAM was invented in the 1960s, 10,000 babies died every year from Rh isoimmunization, and many more suffered from severe brain injuries.

Does RhoGAM cause side effects?

There are always safety concerns about medications. It is true that RhoGAM is a category-C risk. This means the FDA doesn’t have any human studies to say it is safe in pregnancy. 

It’s also true that RhoGAM can cause side effects. These can range from mild symptoms like redness and swelling at the injection site to more severe reactions like anaphylaxis.

But the FDA also says that RhoGAM is not harmful to the baby. Some people were concerned about mercury in these types of medications, but all mercury was removed from RhoGAM in 2018. 

What happens if you don’t get a RhoGAM shot?

Many people have questions about RhoGAM and don’t want to put something in their body that isn't completely necessary. RhoGAM has been in use for over 60 years and is one of the most commonly used medications in the world. It has saved countless lives. 

RhoGAM is considered an essential medication by the World Health Organization (WHO), a designation only given to the most important and life-saving medications. 

There are risks and benefits that come with any decision, especially one that involves your health. It’s a good idea to discuss your concerns with your healthcare provider. There are differences in every person’s situation, and your provider can help you sort through that. 

Why trust our experts?

Written by:

Jennifer Sample, MD

After a fellowship, Dr. Sample worked as the medical director at the University of Kansas Hospital Poison Center (The University Of Kansas Health System Poison Control Center), which served the state of Kansas for poison exposures. In 2007, she returned to Children’s Mercy Hospital in Kansas City, Missouri, as a consultant in clinical pharmacology and medical toxicology.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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