Question: What happens when mother is Rh positive and fetus is Rh negative?

Rh +ve mother and Rh -ve child

Question: What would happen if the mother is Rh positive and having her second pregnancy with a Rh negative child?
Asked by: Anonymous

Insight:
To all those who aren't familiar with the Rh incompatibility explained in the previous post, you may have an insight to it by clicking here.

Answer: When a mother is Rh positive herself, she will not produce antibodies to the fetus.
So there is no question of having the baby in danger.

I'm guessing that your concern is, if a mother conceives a Rh negative fetus, the baby will produce antibodies and attack the mother.

If there is mixing of mother's red blood cells, (which is rare, and considering that a very few red blood cells actually mix and the fetal ability to mount a huge immune response is low) I'd say, it isn't really significant.

Also, the baby will first produce IgM antibodies, no matter whether it is the first, second or third child. IgM can not harm the mother simply because IgM doesn't cross the placenta.