in erythroblastosis fetalis, why is it that only the 2nd baby can get the disease but not the first one?

Question

also, what are the Rh factors of the babies. thank you.

Answer 1

The mother is Rh- and her first child is Rh+. Some of the baby's blood leaks into the mother's blood stream. This set off a reaction where by the mother produces antibodies against the Rh- blood. This does not harm the first child since there is not enough antibody produced. If this happens again with the second child the mother's immune response is quick and deadly.