A doctor takes notes in her office while she is talking to a patient.

Understanding Rh Factors and RhoGam Injections

One of the first blood tests your obstetrician should perform is one to see if you and your baby are both Rh negative or Rh positive. Having a different Rh factors can cause life threatening issues during fetal development, but luckily there’s a treatment for this possible issue. Babies with a different Rh type than their mom can benefit from a maternal Rho D Immune Globulin (RhoGam) injection. Here’s a look at understanding the Rh factor and RhoGam injection.  

What is the Rh Factor?

Most people are familiar with the four general blood types -- A, B, AB, and O -- and everyone is born with a specific blood type. We all also have an additional factor that becomes extremely important during pregnancy. Rh factors are proteins found in red blood cells. If you have the protein, like the majority of people, you’re Rh positive. But if you don’t, you’re Rh negative. 
The Rh factor is passed through DNA, which means babies are either Rh negative or positive based on their parents. If both parents are Rh positive, chances are higher the baby will also be positive. When mom and dad have different Rh factors, the baby could get either one -- and this difference leads to major problems. 

What is Rh Incompatibility?

Rh incompatibility refers to a mother who is Rh negative and a baby who is Rh positive. In general, this isn’t a problem in first pregnancies, because the mother’s body doesn’t usually build up a defense against the baby before the due date. Subsequent pregnancies characterized by Rh incompatibility, however, can be a problem. Without appropriate treatment, an Rh positive baby can develop Rh disease, which may result in “hemolytic anemia,” in which the body destroys red blood cells before it can make new ones. This not only depletes oxygen from the baby, but can ultimately be fatal for the fetus. 

What is the RhoGAM Injection?

RhoGam is an Rh immune globulin injection that keeps the mother and baby’s blood types out of conflict. By getting the shot, the mother’s body can create Rh antibodies without attacking the baby’s blood like a virus. While there are potential side effects from the injection, in most cases the benefits outweigh the risks of the treatment. Still, it is important to discuss any concerns you may have with your obstetrician well in advance. 

When are RhoGam Injections Given?

Again, while first pregnancies with Rh incompatibility are generally fine, following pregnancies can be problematic. Even if something happens and the first pregnancy is not carried to term, additional pregnancies are still a hazard if Rh incompatibility is present. According to the American Congress of Obstetricians and Gynecologists, The RhoGam injection may be given to mothers:
  • Around week 28 to prevent Rh sensitization,
  • Within 3 days of delivery,
  • Following an ectopic pregnancy, miscarriage, or abortion, 
  • Or following amniocentesis, chorionic villus sampling, or other times when blood systems may cross.