Eli5: How does a RhoGAM shot work during pregnancy?


I understand **what** the RhoGAM shot does, that it tells the mother’s immune system to not attack the baby if the baby has a different blood type. But **how** does that happen?

I understand how a flu shot works, but that feels like the total opposite

In: 3

2 Answers

Anonymous 0 Comments

Your immune cells have antibodies that attach to foreign invaders. A Rh-negative person has antibodies against Rh-positive blood cells. When an immune cell detects that its antibodies have been activated, it’ll multiply a bunch. Some of the resulting cells will fight the invader, others will hang around in case it returns years later.

RhoGAM floods your blood with antibodies against the same foreign blood cells, and those antibodies attach to them before your immune cells get a chance to do so. This means your immune system can’t “see” them, and doesn’t create an army in order to fight them.

It’s quite a bit more complicated, but this is the gist of it.

Anonymous 0 Comments

Adding to what u/GalFisk said, which was a great explanation. Because its a dose of outside antibodies (not a vaccine which teaches your body how to make something new) those antibodies will either get used up or degrade over time (approx 13 weeks) RhoGAM is therefor given any time there is a chance the mother could be exposed to fetal blood, which can be more than once in each pregnancy (bleeding, surgery, birth, etc)