Understanding the Links Between the Rh Factor and the RhoGAM Shot

While being Rh incompatible might sound alarming, you can get a simple injection called RhoGAM to protect your future babies from potential complications. Here’s everything you need to know about your Rh factor, how it could affect your pregnancy, and how a RhoGAM shot will help.

The Rhesus (Rh) factor is a protein on the surface of your red blood cells. 1 If you have a positive blood type, you’re Rh-positive, and if you have a negative blood type, you’re Rh-negative.

In the US, roughly 85% of the population is Rh-positive. 2

Why does the Rh factor matter in pregnancy?

If you’re Rh-negative and your baby’s other parent is Rh-positive, this can cause complications if she inherits their Rh-positive blood type.

Suppose some of her blood cells enter your bloodstream. This can happen during delivery or certain prenatal procedures (such as amniocentesis or chorionic villus sampling), as well if you have any pregnancy complications involving abdominal trauma or vaginal bleeding. 3

If this happens, your body may see your baby’s Rh-positive blood cells as a threat and produce antibodies to attack them.

Your antibodies can then enter your baby’s body in various ways (e.g., by passing through the placenta) and attack the baby’s red blood cells, leading to complications like:

• Hemolytic disease of the newborn (HDN): If your baby has this condition, it means your antibodies are attacking her red blood cells too quickly for her to replace them. Symptoms of HDN include edema (swelling under the skin), newborn jaundice, and anemia. 4
• Brain damage: When your antibodies break down your baby’s red blood cells, it can also cause an overproduction of bilirubin. Too much bilirubin also causes jaundice, and in severe cases, it can cause brain damage and death. 3
• Hydrops fetalis: Rh incompatibility can cause a nasty variant of hydropos fetalis (immune hydropos fetalis) to show up. This condition may cause your baby to retain too much fluid in her body once she’s born, resulting in severe swelling. It may even lead to heart failure. 5
• Hypotonia: After she’s born, your baby may have low muscle tone, known as hypotonia. This can make her extremely lethargic and may even slow down some of her developmental milestones, like her fine motor skills or the ability to hold her head up. 3 6

To avoid all of that, if you and your baby are Rh incompatible, your OB will recommend that you get a RhoGAM shot. This injection contains Rh immunoglobulin (RhIg), an antibody derived from human blood. 7

This may be necessary if you conceive again in the future, too (Rh incompatibility is risky for future pregnancies). 2

When you get a RhoGAM shot, your immune system stops recognizing and reacting to your baby’s Rh-positive fetal blood cells. That’s because the RhoGAM antibodies attach to any Rh-positive cells in your bloodstream, effectively hiding them from your immune system.

Your doctor will administer your RhoGAM shot when you’re 28 weeks pregnant, as well as within 72 hours of giving birth if your baby is Rh-positive. 8 If it turns out that they’re Rh-negative, there’ll be no need for that second shot.

Safety and side effects

The RhoGAM shot is completely safe—these shots have been used since the 1960s and have a strong safety record. 9 Still, you might experience some mild side effects when you get the shot, such as: 10

• Soreness or redness at the injection site
• Mild fever and chills
• In rare cases, a (treatable) allergic reaction

How does a RhoGAM shot affect future pregnancies?

Each RhoGAM shot protects you for about 13 weeks. 11 You’ll need a RhoGAM shot with each pregnancy if you are Rh-negative and the baby’s other parent is Rh-positive or doesn’t know their Rh status.

Getting the shot won’t affect your reproductive health or your ability to conceive in the future.

Will your insurance cover a RhoGAM shot?

Your doctor needs to prescribe a RhoGAM shot for you, and how much it’ll cost depends on your insurance coverage. Assuming you’re insured, your provider will likely cover it, but it’s best to check with them to be sure.

Technically, you can skip out on the RhoGAM shot, but experts don’t recommend it if you and your baby are Rh-incompatible. It’s the best thing to do to ensure your baby’s health and safety.

Take your OB’s word on when to get it (i.e., what week of your pregnancy), too. RhoGAM loses effectiveness once you’ve developed antibodies against your baby’s red blood cells, so this isn’t something to drag your feet on. 12

If you opt to skip getting a RhoGAM shot, you might develop complications if you decide to get pregnant again. Your antibodies will always attack an Rh-positive fetus, making your pregnancy at risk. Your doctor will need to keep a close eye on your pregnancy, and your baby might need blood transfusions. 12

Rh incompatibility between you and your baby can cause serious issues. However, none of that’s inevitable; Rh disease is easily preventable as long as you take your RhoGAM shot.

Talk to your OB about getting your Rh factor tested, as well as any concerns you have about getting a RhoGAM shot.