Why is Rhogam (Rh immune globulin) necessary?

When a woman comes in for her initial prenatal visit some of her blood is taken in order to run tests. A “type and screen” are part of these tests and what that means is that we want to know the woman’s blood type (A, B, AB, O), Rh factor (positive or negative) and if there are any antibodies present in her blood. This information is important because women who are Rh Negative will more than likely need to receive Rhogam. Let’s say that your blood type is A Negative. The next step would be to find out your partner’s blood type. If he is Rh Negative and you don’t have any antibodies in your blood, then you do not need Rhogam. But if he is Rh Positive then you will need to receive Rhogam at around 28 weeks of your pregnancy. Then when your baby is born we would have to test his or her blood as well. If your baby is Rh Negative you will not need Rhogam after delivery, but if he or she is Rh Positive, then you will need Rhogam after delivery.

Let’s try to understand the science behind this process. Our bodies are programmed to fight off unwanted viruses, bacteria, fungi, and other threats to our system. We achieve this by building antibodies that recognize an intruder that made us sick; the next time it tries to attack, our body’s defenses will detect it and fight it off. If a mother is Rh Negative and her baby is Rh Positive there is a risk that the fetal blood will enter mom’s circulation and mom’s body will think that it needs to respond as if there is an intruder.

Giving Rhogam allows baby’s blood to bind to it so that mom’s blood does not see any threat and does not make antibodies against Rh Positive babies.  Rhogam is effective for about 12 weeks and that’s why mom should receive another dose after delivery if the baby is RH positive. Moms should receive another dose of Rhogam after a miscarriage, accidents to the abdomen, or other instances when there is a risk of baby’s blood mixing with mom’s blood. Rh Negative moms will need to receive Rhogam with every pregnancy if the baby’s father is Rh Positive.

If a woman develops Rh Positive antibodies she will have a high risk of miscarriage. If a baby is exposed to these antibodies there is a high risk for a pre-term delivery, severe anemia that requires a blood transfusion, and sadly even death. That is why Rhogam is a simple enough solution to a potentially big problem.

Written by: Sabely (Student Midwife)