I don't know about cells of the baby remaining in the body of the mother, but in the link you posted it says that HDN is caused (a) in the baby (b) by IgG antibodies (not cells).
I don't know about cells of the baby remaining in the body of the mother, but in the link you posted it says that HDN is caused (a) in the baby (b) by IgG antibodies (not cells).