How does Rhogam work?

In my last post, I explained how a Rhesus negative mother who has been “sensitized” from her previous pregnancy literally attacks any subsequent fetus that is Rhesus positive. For clarity, sensitization here means that there has been some exposure and you have produced some Anti-D antibodies against Rhesus positive blood. This is almost inevitable during childbirth or miscarriage after 12 weeks of pregnancy as some of your baby’s blood mixes with yours.

Therefore, you are advised to take a single intramuscular injection of Rhogam within 72 hours of every delivery or miscarriage. There are other situations that may warrant taking Rhogam and there are a few situations when Rhogam is not necessary. I have made a list of such situations in a previous post.

So, what is Rhogam?

Rhogam is a popular trade name for Anti-D Immunoglobulin and a look-alike of the Anti-D antibodies that you would produce when you are exposed to any Rhesus positive blood. What Rhogam does is to stop you from being sensitized despite the fact that you have been exposed. Essentially, it blocks your immune system from declaring war against your Rhesus positive baby.

Before you are given Rhogam, you will be asked to do a blood test called antibody testing. We want to know if you have been sensitized and to what extent. Similarly, in case of trauma or bleeding during pregnancy, you will do a test called Kleihauer–Betke test to check the amount of your baby’s blood that has mixed with yours and calculate the amount of Rhogam we need to neutralize the effect.

If you have been sensitized, it will not make sense to give you Rhogam because your antibodies are already prepared to fight. The best we can do is to continue monitoring your antibody levels and take necessary action when it reaches a threshold. But if you have not yet been sensitized, Rhogam helps to protect your baby as we have discussed above.

When should you receive Rhogam? I will refer you back to that post where I explained the timing and dosage of the injection. This injection is quite expensive, so I advise couples to save enough money ahead of time, unless you have health insurance coverage.

You might be wondering how Rhogam itself does not affect your baby! Your concern is valid, but the good news is that Rhogam does not cross the placenta, so it won’t go and destroy your baby’s blood.

Like any other medication, you may experience some side effects like pain, discomfort, weakness or dizziness. These are mild and transient effects but always inform your doctor if you have any concern.

Let me know if you have any question in the comment box. Stay safe!

©Doctor KT

2021