RhoGAM Shot For Rh Incompatibility: Why You May Need It

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Parenthood

Pregnant and Rh Negative? Why You May Need a RhoGAM Injection

Medically reviewed by Dena Westphalen, PharmD — Written by Donna Christiano on October 30, 2019

Rh factor
Rh incompatibility
Why RhoGAM
How it's given
Side effects
Risks
Cost
Takeaway

When you’re pregnant, you may learn that your baby isn’t your type — blood type, that is.

Every person is born with a blood type — O, A, B, or AB. And they’re also born with a Rhesus (Rh) factor, which is positive or negative. You inherited your Rh factor from your parents, just like you inherited your mom’s brown eyes and your dad’s high cheek bones.

Pregnancy is really the only time when there might be some bad blood (pun intended!) between you and your Rh factor.

When you’re Rh negative and the baby’s biological father is Rh positive, some life threatening complications can arise if the baby inherits dad’s positive Rh factor. This is called Rh incompatibility, or Rh disease.

But don’t push the panic button just yet. While it’s important to be screened for the disease, Rh incompatibility is rare and preventable.

To offset problems, your doctor can give you a shot of RhoGAM — generic: Rho(D) immune globulin — at about 28 weeks of pregnancy and whenever your blood may mix with your baby’s, like during prenatal tests or delivery.

What is Rh factor?

Rh factor is a protein that sits on red blood cells. If you have this protein, you’re Rh positive. If you don’t, you’re Rh negative. Just 18 percent of the population has an Rh negative blood type.

When it comes to your health, it really doesn’t matter which you have — even if you ever need a blood transfusion, doctors can easily make sure you receive Rh negative blood. However, concerns come up during pregnancy (what isn’t a concern during pregnancy?) when negative and positive blood have the potential of mixing.

Rh incompatibility

Rh incompatibility occurs when an Rh negative woman conceives a baby with an Rh positive man. According to the National Heart, Lung and Blood Institute:

There’s a 50 percent chance your baby will inherit your negative Rh factor, which means you’re both Rh compatible. All is AOK, with no treatment needed.
There’s also a 50 percent chance your baby will inherit their father’s Rh positive factor, and that results in Rh incompatibility.

Determining Rh incompatibility can be as simple as taking blood samples from you, and, ideally, the baby’s dad.

If both parents are Rh negative, the baby is too.
If both parents are Rh positive, the baby is Rh positive.
A blood test is usually done at one of your first prenatal visits.

And — get used to those needle sticks — if you’re Rh negative, your doctor will also do a screening blood test to check for Rh antibodies.

Antibodies are proteins your immune system makes to fight off substances foreign to your body (like Rh positive blood).
If you have antibodies, it means you’ve already been exposed to Rh positive blood — from a previous delivery, for example, an abortion, or even a mismatched blood transfusion.
Your baby is at risk for Rh incompatibility if their dad is Rh positive.
You may need this screening test several times throughout pregnancy to gauge your level of antibodies (the higher they are, the more severe your baby’s complications may be).
If you do have antibodies, RhoGAM won’t help your baby. But don’t freak out. Doctors can:
- order screening tests, like an ultrasound, to monitor your baby’s development
- give your baby a blood transfusion via the umbilical cord, before your baby ever checks out of the Comfort Inn that is your womb
- suggest an early delivery

More reasons to stay calm:

Sometimes your baby’s Rh incompatibility can produce only mild complications that don’t require treatment.
First pregnancies aren’t usually affected by Rh incompatibility. That’s because it can take longer than 9 months for an Rh negative mom to make antibodies that fight Rh positive blood.

Why RhoGAM is used

An Rh negative mom (not her baby) will receive RhoGAM at several points throughout pregnancy when the Rh factor of the dad is positive or unknown. This prevents her from making antibodies to Rh positive blood — antibodies that can destroy her baby’s blood cells.

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

at 26 to 28 weeks of pregnancy, when the placenta can start to thin and, although unlikely, blood can transfer from baby to mom
after an abortion, stillbirth, miscarriage, or an ectopic pregnancy (a pregnancy that develops outside the uterus)
within 72 hours of delivery, including a 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
after trauma to the midsection, which might happen after a fall or a car accident
any manipulation to the fetus — for example, when a doctor turns an unborn baby settled in the breech position
vaginal bleeding during pregnancy

How it’s administered

RhoGAM is a prescription drug typically given by injection into a muscle — often in the backside, so just another indignity you’ll deal with while pregnant. It can also be given intravenously.

Your doctor will decide what’s the appropriate dose for you. RhoGAM is effective for about 13 weeks.

Common side effects of RhoGAM

RhoGAM is a safe drug with a 50-year track record of protecting babies from Rh disease. According to the drug’s manufacturer, the most common side effects occur where the shot is given and include:

hardness
swelling
pain
aches
rash or redness

A less common side effect is a slight fever. It’s also possible, though less likely, to have an allergic reaction.

The shot is only given to you; your baby encounters no side effects. RhoGAM isn’t for you if you:

already have Rh positive antibodies
are allergic to immunoglobulin
have hemolytic anemia
have had vaccines recently (RhoGAM reduces their effectiveness)

Risks of the RhoGAM shot — and not getting it

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 fact, 1 Rh negative pregnant woman in 5 will become sensitive to the Rh positive factor if she doesn’t receive RhoGAM. That means, that her baby can be born with one or more of the following things:

anemia, a lack of healthy red blood cells
heart failure
brain damage
jaundice, a yellowish tinge to skin and the eyes due to an improperly functioning liver — but note, jaundice is fairly common in newborns

Costs and options

Prices and insurance coverage for RhoGAM vary. But without insurance, expect to spend a couple to several hundred dollars per injection (ouch — that’s more painful than the pinch of the needle!). But most insurance companies will cover at least some of the cost.

Talk to your doctor about whether the generic version of RhoGAM — Rho(D) immune globulin — or a different brand of the drug is more cost effective.

The takeaway

Rh disease is uncommon and preventable — arguably a “best-case scenario” disease in that sense. Know your blood type, and, if possible, that of your partner’s. (And if it’s before pregnancy, all the better.)

If you’re Rh negative, talk to your doctor about whether you’ll need RhoGAM and when the best time is to get it.

Parenthood
Pregnancy
Pregnancy Complications

How we reviewed this article:

SourcesHealthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Mayo Clinic Staff. (2018). Rh factor blood test.https://www.mayoclinic.org/tests-procedures/rh-factor/about/pac-20394960
Rh disease. (2017).https://www.marchofdimes.org/complications/rh-disease.aspx
Rh factor: Management and treatment. (2018).https://my.clevelandclinic.org/health/diseases/21053-rh-factor/management-and-treatment
Rh incompatibility. (n.d.).https://www.nhlbi.nih.gov/health-topics/rh-incompatibility
Rh negative blood type and pregnancy. (2013).http://www.midwife.org/acnm/files/ccLibraryFiles/Filename/000000003906/Rh_negative_blood_pregnancy.pdf
Scientific facts: Negative blood types. (n.d.).https://obi.org/blood-donation/scientific-facts/

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Medically reviewed by Dena Westphalen, PharmD — Written by Donna Christiano on October 30, 2019

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