When Is It Too Late to Get RhoGAM Shot?

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It’s too late to get a RhoGAM shot when you’ve already been sensitized, which means that your baby’s blood has already mixed with yours, causing your body to create antibodies to attack your baby’s red blood cells. It won’t be a problem on your first pregnancy because blood mixing commonly occurs during childbirth, and it takes approximately one month before your body can create specific antibodies for Rh-positive blood. But, it would be dangerous if you conceive another Rh-positive baby. While in the womb, your baby may develop fetal anemia leading to severe and fatal diseases such as erythroblastosis fetalis and hydrops fetalis.

Everyone is born with a blood type and Rh (rhesus) factor which, tells us about the specific antigens and antibodies present in our blood. Your body recognizes antigens as a “threat,” such as viruses and bacteria, which trigger your immune system to create antibodies to fight a specific type of antigen. 

Everyone is born with a blood type, which can be A+, A-, B+, B-, AB+, AB-, O+, or O-. An Rh-positive (e.g., A+) means that an Rh protein is present in your red blood cells and is positive for D antigen, while Rh-negative (e.g., A-) tells that you have no Rh protein and negative for D antigen. 

When Rh(D)-positive blood enters the bloodstream of an Rh-(D) negative person, the body will automatically create anti-D antibodies to kill those RhD positive red blood cells.

Only about 18% of people in the United States have Rh-negative blood type.

Your blood type is pre-determined by your parents’ blood types, like how you inherit their physical traits or features. So your doctor will request blood testing to determine your blood type and Rh factor in your prenatal checkups.

It’s essential to know this to avoid mismatched blood transfusion or if you must get RhoGAM shots to prevent Rh incompatibility between you and your baby.

What is a RhoGAM shot?

RhoGAM or Rho (D) immune globulin is a specific brand name of anti-D immune globulin or RhIG. It’s a drug made up of manufactured antibodies or immunoglobulin extracted from a sterilized and donated human plasma (the liquid part of the blood).

RhoGAM shots effectively treat Rh-positive patients suffering from a blood disorder known as thrombocytopenic purpura (ITP). It is also used in pregnant women with Rh-negative blood to prevent Rh incompatibility between the mom and the baby. 

How does a RhoGAM shot work?

If you are Rh-negative and your partner is Rh-positive, your baby may inherit its father’s Rh protein.

In such circumstances that your baby’s blood mixes with yours during pregnancy, your body won’t recognize your baby’s Rh protein posing it as a “threat” or a “foreign body.” As a result, your immune system will attack your baby’s blood. This condition is called Rh incompatibility. 

When there is a possible leak of your baby’s blood in your placenta, RhoGAM will “mask” the fetal blood that has entered your bloodstream so that your immune system won’t be able to see it and start an immune response. 

When to get a RhoGAM shot

Skip the skepticism because RhoGAM shots are safe! They’ve undergone thorough clinical screening and sterilization processes to ensure that pathogens in the donated blood are killed.

Getting RhoGAM shots is the only preventive measure to avoid future complications due to Rh incompatibility. 

Pregnant women with Rh-negative blood are highly recommended to get RhoGAM shots during 26-28 weeks of pregnancy. It will decrease the potential risk of Rh sensitization. Although your body won’t have enough time to create antibodies to attack your first baby before it is born, it would put your subsequent pregnancies at significant risk.

You will also get another dose of RhoGAM shot 72 hours after giving birth to an Rh-positive baby, whether you had a standard or Cesarean delivery. Because it is when you give birth to the baby, large amounts of blood mixing and Rh sensitization occur. 

Your doctor will also recommend you to get RhoGAM shots as soon as possible when you have:

What happens if you don’t get RhoGAM shot?

There are about 13%-16% chances that you will become Rh sensitized. It means that your system will become sensitive to Rh-positive blood. And when you are pregnant with another Rh-positive baby, you will automatically produce antibodies that can cross the placenta and kill your baby’s red blood cells.

Getting a RhoGAM after Rh sensitization won’t be effective anymore.

While this won’t harm you, it would likely put your baby’s health in danger and cause complications in your subsequent pregnancy.

Your baby may develop one or more of the following:

Erythroblastosis fetalis or hemolytic disease of the newborn (HDN)

Although this condition may develop due to ABO or Rh factor incompatibility, it’s more threatening if caused by Rh-incompatibility.

Babies born with erythroblastosis fetalis may appear pale and swollen (edema) with yellowish skin and eyes (newborn jaundice).

Your newborn may also have:

  • Anemia or low red blood cell count
  • Abnormal or larger-sized liver or spleen

In worst cases, erythroblastosis fetalis may lead to a severe and fatal disease called hydrops fetalis.

Hydrops fetalis

Nearly half of babies born with hydrops fetalis in the United States die shortly after birth. It is a condition that may develop due to severe cases of Rh-incompatibility or when your baby’s system has difficulties regulating its bodily fluids due to some underlying diseases.

Babies with hydrops fetalis have too much fluid build-up in the tissues surrounding their heart, lungs, or abdomen. When there is too much fluid in the spaces around their hearts, they may experience difficulty in pumping blood thus, causing more complications to arise or, worse, death.

How are they diagnosed?

It’s hard to tell if your baby has developed one of the diseases stated above, as you will experience no symptoms. But, if you’re tested to have anti-D antibodies in your blood during your blood testing, your doctor will have to run more tests on you every two to four weeks.

If the levels of your antibodies increase, your baby is at risk of developing Rh diseases. In addition, your doctor may have to test the blood flow of your baby’s cerebral artery to detect fetal anemia which, could indicate erythroblastosis fetalis.

Early signs of hydrops fetalis may show in an ultrasound during your prenatal checkups.

Your doctor may also recommend more tests on you such as:

How are they treated?

In their mom’s womb, babies who develop erythroblastosis or hydrops fetalis may need intrauterine blood transfusions to reduce anemia and increase their survival until birth.

Your doctor may also need to induce early delivery through medications or once your baby’s heart and lungs mature enough which, is done in an emergency Cesarean section (C-section). 

When the baby is born, intensive medical treatment and monitoring are given for at least 3-4 months or may take longer for hydrops fetalis.

These treatments include:

  • Further blood transfusions to reduce low blood pressure. Your baby may also need direct red blood cell transfusions. 
  • Breathing support through a ventilator or mechanical breathing machine
  • Medications to remove excess fluid and control heart failure 

However, babies born with hydrops fetalis have relatively lower chances of survival.

They are also at risk of severe conditions like:

  • Heart failure
  • Brain damage
  • Hypoglycemia or deficient levels of blood sugar (glucose)
  • Seizures or uncontrolled tremors, twitching or jerking movements

Side effects of RhoGAM shots

A pregnant woman is experiencing back pain after having her RhoGAM shot

RhoGAM shots are injected into your muscle, often in your backside. After receiving the medicine, you may deal with mild symptoms such as:

  • Swelling, redness, or itching at the injection site
  • Pain and aches
  • Weakness or fatigue

Other less common side effects include:

Please contact your health care provider if other unusual symptoms occur, such as intense headache due to high blood pressure, difficulty or pain when urinating, trouble breathing, excessive swelling, and bruising.


How long does it take for Rh antibodies to form?

Once your baby’s blood mixes with yours and Rh sensitization occur, it takes approximately one month for the antibodies to develop.

As stated before, sensitization occurs during childbirth where a huge amount of your baby’s blood mixes with yours. That’s why your first newborn isn’t at risk for Rh incompatibility because it will be born before the antibodies can cross your placenta and harm your baby.

Can I get RhoGAM after 28 weeks?

Although most doctors recommend getting RhoGAM shots at 28 weeks gestation, you can still receive them later.

Some pregnant women report not getting their shots until 30-32 weeks, and their babies were born healthy. But, you shouldn’t delay nor skip your RhoGAM shot once your doctor recommends you to get one immediately.

There are still small chances that you’ll be sensitized before giving birth. Once you’re sensitized, there’s no point in getting a RhoGAM shot because it won’t be effective anymore.

Why do some pregnant women don’t get a RhoGAM shot?

Well, the only reason could be their doctors didn’t recommend them to get one in the first place because they have:

– Already been sensitized, meaning there’s now Rh antibodies in their blood
– Rh-positive blood type
– Allergies to immunoglobulin
– Have hemolytic anemia
– Have had vaccines recently (RhoGAM may reduce their effectiveness).

It’s also best if you don’t get any vaccines about three months after receiving RhoGAM.

You may also skip a RhoGAM shot if you’re Rh-negative and your partner’s blood type is also Rh-negative because it would be impossible for your baby to have an Rh-positive blood type. So there’s no chance that you both (mom and baby) will develop Rh incompatibility.

Do I need a RhoGAM shot every time I bleed?

Not really. You just need to get the shot within 72 hours after your bleeding. Be sure to contact your doctor immediately when early pregnancy spotting and bleeding occurs, especially before you reach your third trimester.


You shouldn’t skip your RhoGAM shot when you’re tested to have Rh-negative blood nor wait until the baby is born. You should also get another shot within 72 hours after giving birth to an Rh-positive baby.

In such situations, when you’ve received it late, you shouldn’t worry much if you got the first dose within your 28 weeks of pregnancy. RhoGAM will stay effective for about 13 weeks, and your baby should be born by then. But, it will be too late to get a shot after you’ve already been sensitized.

If a blood test or an ultrasound confirms Rh sensitization, your doctor will do routine checkups to monitor the levels of your antibodies and your baby’s condition and development.

Remember that RhoGAM shots have saved thousands of babies every year in the United States, and it is the only way you can prevent your fetus from developing severe diseases that may cause death.

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Reana Jean Cuevas
Mabuhay! I'm Reana Jean Cuevas. A healthy body means living well with no worries-just happiness and more life adventures. Taking care of my body and well-being is an investment for my career and future. I was a volunteer at the Philippine Red Cross. I joined the training to become a first-aider and be able to provide other health and safety services in my community. I love discussing anything but mainly first-aid, home remedies, and women's health.

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