Why does an Rh reaction (second child) cause much more severe anemia than ABO (per RR Path)? From what I can tell from reading, both involve fetal splenic macrophage destruction of the IgG-coated RBCs. It does appear that he suggests that in ABO the macros don't phagocytose them completely (resulting in spherocytes) whereas there's no mention of such thing for Rh. I suppose that would explain things (some RBCs are simply deformed rather than destroyed) . . . assuming that's the reason. But does anyone have a clue why?