When do you get rhogam shot in second pregnancy

If you are Rh-negative, most doctors will advise that you get a RhoGAM shot after you've experienced a miscarriage, ectopic pregnancy, or other pregnancy loss. Getting a RhoGAM or other Rh immune globulin shot is a precaution against a situation called Rh incompatibility, which could affect future pregnancies and cause hemolytic disease in the newborn.

A RhoGAM shot injects Rh-positive proteins, which prevent you from developing certain antibodies that make you sensitized to RH-positive blood. It is often given to those who have experienced pregnancy loss to prevent future pregnancy loss.

If you are Rh negative, meaning that your blood does not contain the Rh factor protein, your doctor will probably recommend that you get an Rh immune globulin shot (such as RhoGAM) within 72 hours of the start of your bleeding.

• Why get the shot? With the shot you have lower odds of developing antibodies (becoming sensitized) against Rh-positive blood from this pregnancy; if you have circulating antibodies against Rh factor, you can face problems in future pregnancies.
• What if you wait too long? If given later than 72 hours after the start of the miscarriage, the shot is not likely to make a difference. However, it has been more than three days since your miscarriage, however, don't panic. The odds that you have become sensitized against Rh factor are low.
• Is it necessary? Although there's no strong evidence that the shot is totally necessary after a first-trimester pregnancy loss, the shot is low-risk, so doctors recommend it after any pregnancy bleeding because of the theoretical risk of Rh sensitization.

It is still a good idea to get it within the recommended time span if you can, as it makes the small risk of Rh sensitization even lower. There's much more evidence on the shot's necessity after a later pregnancy loss or after giving birth.

If you are concerned, you can ask your doctor about a blood test to check for RH sensitization so that you can set your mind at ease.

Rh factor is a protein that the majority of people carry in their blood. Roughly 85% of the population is Rh-positive, and Rh status is genetically determined.

• If the baby has one parent who is Rh-negative and one who is Rh-positive, the baby has at least a 50% chance of being Rh-positive (Rh-positive status is a dominant genetic trait).
• Birthing parents who are Rh-positive, and who are Rh-negative with Rh-negative partners, do not need to worry about RhoGAM shots because Rh incompatibility is impossible.

In first pregnancies, Rh sensitization is rarely a problem because the parent's blood and the baby’s blood typically do not interact directly until delivery—but if Rh-positive blood (such as from the baby) enters the Rh-negative parent's blood, their immune system may develop antibodies against Rh factor.

If these antibodies then enter an Rh-positive baby’s bloodstream, the antibodies can begin to attack the baby’s blood, causing jaundice or more severe symptoms if left untreated.

RhoGAM pre-stocks the parent's blood with the antibodies to the Rh factor protein. This prevents their immune system from needing to create antibodies to Rh factor in the event of encountering Rh-positive blood.

Injecting the antibodies is safer than risking sensitization. This is because RhoGAM antibodies eventually clear the bloodstream, meaning that if the parent's blood mixed with the baby’s in the future, the immune system would not have learned to create antibodies against Rh factor and the baby would not get anti-Rh antibodies.

If a birthing parent's blood is sensitized to Rh factor, the sensitization may be permanent and they risk delivering anti-Rh antibodies to future babies.

As a part of the blood testing in standard prenatal care, most doctors check the blood type in order to identify Rh incompatibility. Originally, recommendations were to give the injections to people who had given birth. The recommendations then changed to include a RhoGAM shot around 28 weeks of pregnancy.

Although few studies exist on using Rh immune globulin for first-trimester miscarriages, many doctors do recommend them because of a theoretical risk of sensitization after miscarriages with the idea that the potential benefits outweigh the minimal risk.

The shot needs to be given within about 72 hours of the onset of the miscarriage in order to be effective.

If you did not get a RhoGAM shot, do not panic. Remember that the risk of sensitization after a miscarriage is relatively small.

However, you should inform your doctor about your concern. Your doctor can order a blood test to check your Rh sensitization status.

In the event that you did develop anti-Rh antibodies, treatments for Rh incompatibility do exist and your doctor will know to observe your future pregnancies closely for signs of problems so as to intervene early if needed.

Verywell Family 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.

1. Karanth L, Jaafar SH, Kanagasabai S, Nair NS, Barua A. Anti-D administration after spontaneous miscarriage for preventing Rhesus alloimmunisation. Cochrane Database Syst Rev. 2013;(3):CD009617. doi:10.1002/14651858.CD009617.pub2

2. National Heart, Lung, and Blood Institute. Rh incompatibility.

3. March of Dimes. Rh disease.

4. Liumbruno GM, D'Alessandro A, Rea F, et al. The role of antenatal immunoprophylaxis in the prevention of maternal-foetal anti-Rh(D) alloimmunisation. Blood Transfus. 2010;8(1):8-16. doi:10.2450/2009.0108-09

• Hannafin B, Lovecchio F, Blackburn P. Do Rh-negative women with first trimester spontaneous abortions need Rh immune globulin?. Am J Emerg Med. 2006;24(4):487–489. doi:10.1016/j.ajem.2006.01.020

Rh factor (short for Rhesus factor) is a protein that most people have on the surface of their red blood cells.

At your first prenatal visit, your blood will be tested to determine your blood type and your Rh status. If you do have the Rh factor, as most people do, your status is Rh positive. (About 85 percent of Caucasians are Rh positive, as are 90 to 95 percent of African Americans and over 95 percent of American Indians and Asian Americans.)

If you don't have Rh factor, you're Rh negative, and you'll need to take certain precautions during your pregnancy.

Why is it a problem if I'm Rh negative?

If you're Rh negative, there's a good chance that your blood could react with your baby's blood, which is likely to be Rh positive. (This is called Rh incompatibility.) You probably won't know this for sure until your baby is born, but in most cases you have to assume it's positive, just to be safe.

Being Rh incompatible isn't likely to harm you or your baby during your first pregnancy. But if your baby's blood directly interacts with yours (as it can at certain times during pregnancy and at birth), your immune system will start to produce antibodies against this Rh positive blood. If that happens, you'll become Rh sensitized — and the next time you're pregnant with an Rh positive baby, those antibodies may attack your baby's red blood cells.

Fortunately, you can avoid becoming Rh sensitized by getting an injection of a drug called Rh immune globulin (RhoGAM). Doctors give it whenever there's a chance that your blood has been exposed to the baby's blood and also preventatively in the early third trimester and postpartum.

If you're Rh negative and you've been pregnant before but didn't get this shot, another routine prenatal blood test will tell you whether you already have the antibodies that attack Rh positive blood. (You could have them even if you miscarried the baby, had an abortion, or had an ectopic pregnancy.)

If you don't have the antibodies, then the shot will keep you from developing them.

If you do have the antibodies, it's too late to get the shot. Your provider will make a plan for you and your baby to be monitored through your pregnancy with blood work first and then possibly special ultrasound tests to detect fetal anemia. You may be referred to a maternal-fetal medicine specialist for consultation or treatment.

What are the chances that my baby and I are Rh incompatible?

Rh status is inherited. If your baby's father is Rh positive — as most people are — you have about a 75 percent chance of having an Rh positive baby. So if you're Rh negative, it's likely that you and your baby are Rh incompatible. In fact, your healthcare practitioner will assume you are, just to be safe.

There's no harm in getting the Rh immune globulin shot, even if it turns out that it wasn't necessary.

How could my baby's blood leak into mine?

Normally during pregnancy, your baby's blood stays separate from yours. The placenta allows for exchange of oxygen, nutrients, and fluids, but not red blood cells. In fact, your blood is not likely to intermingle in any significant way until you give birth. That's why Rh incompatibility is usually not a problem for your first baby: If your blood doesn't mix until you're in labor, the baby will be born before your immune system has a chance to produce enough antibodies to cause problems.

Times when your baby's blood can leak into yours:

Delivery: You'll need a shot after the birth if your newborn is found to be Rh positive. Since it's possible you were exposed to your baby's blood during delivery, the shot will prevent your body from making antibodies that could attack an Rh positive baby's blood during a future pregnancy.

(Your delivery team will take a blood sample from your newborn's heel or from their umbilical cord just after they're born to test for several things, including Rh factor, if necessary.) Without treatment, there's about a 15 percent chance that you'll produce antibodies, but with treatment, the chance is close to 0 percent.

In the third trimester: A small number of Rh negative women (about 2 percent) somehow develop antibodies to their baby's Rh positive blood during their third trimester. So you'll also be given shot of Rh immune globulin at 28 weeks that covers you until childbirth.

Other opportunities: And you'll need a shot any other time that your baby's blood might mix with yours, including if you have:

If you find yourself in any of these situations, remind your caregiver that you're Rh negative, and make sure you get the shot within 72 hours.

How does the shot prevent me from developing antibodies?

The Rh immune globulin shot consists of a small dose of antibodies, collected from blood donors. These antibodies kill any Rh positive blood cells in your system, which seems to keep your immune system from developing its own antibodies. The donated antibodies are just like yours, but the dose isn't large enough to cause problems for your baby.

This is called passive immunization: For it to work, you need to get the shot no more than 72 hours after any potential exposure to your baby's blood. The protection will last for 12 weeks. If your practitioner suspects that more than an ounce of your baby's blood mixed with yours (say, if you've had an accident), you might need a second shot. If necessary, special blood tests can be done to measure exactly how much fetal blood has mixed with yours.

You'll get the injection in the muscle of your arm or buttocks. You may have some soreness at the injection site or a slight fever. There are no other known side effects. The shot is safe whether your baby's blood is really Rh positive or not.

What will happen to my baby if I develop the antibodies?

First, keep in mind that this is highly unlikely if you're receiving good prenatal care and are being treated with Rh immune globulin when necessary. Even without treatment, your chances of developing the antibodies and becoming Rh sensitized are only about 50 percent even after several Rh incompatible pregnancies.

If you didn't get the shot, though, and you became Rh sensitized and your next baby is Rh positive, your antibodies can cross the placenta and attack the Rh factor in your baby's Rh positive blood as if it's a foreign substance, destroying his red blood cells and causing significant anemia. In rare cases, a more serious condition, called hemolytic disease of the fetus (HDFN) can develop if an Rh negative mother does not receive Rh immune globulin treatment and her child is positive. This condition greatly increases the risk of severe anemia, jaundice, congestive heart failure, or even death.

The good news is that doctors are finding new ways to save babies who develop Rh disease. Your practitioner can monitor your level of antibodies and keep tabs on your baby's condition during pregnancy to see whether they're developing the disease. She may check on the condition of your baby's red blood cells using Doppler ultrasound or amniocentesis.

If your baby is doing well, you might be able to carry them to term without complications. After birth, they may be given what's called an exchange transfusion to replace their diseased Rh positive red blood cells with healthy Rh negative cells. This stabilizes the level of red blood cells and minimizes further damage by antibodies circulating in their bloodstream.

Over time these donated Rh negative blood cells will die off and all your baby's red blood cells will be Rh positive again, but by that time, the attacking antibodies will be gone.

If your baby's in distress or severely anemic, they might be delivered early or given transfusions through the umbilical cord. The survival rate for babies who receive a transfusion in utero is as high as 80 to 100 percent, unless they have hydrops (a complication caused by severe anemia), in which case the chances of survival are about 40 to 70 percent.

What about future pregnancies?

Once you're sensitized, you have the antibodies forever. And you produce more with each pregnancy, so the risk of Rh disease is higher for each subsequent baby.

Your Rh status is one of many things your early blood test will determine. Learn what else your provider will be checking in our article on Common first trimester blood tests.

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