If fertilization takes place between gametes of Rh^– female and Rh⁺ male then the resulting foetus’ blood is Rh⁺ . The Rh⁺ blood of the fetus stimulates the formation of anti Rh factors in the mother’s blood. In second pregnancy (with Rh⁺ foetus), the anti Rh factors of the mother’s blood destroy the fetal red blood corpuscles. This is called erythroblastosis fetalis. New born may survive but it is often anaemic. The Rh^– child does not suffer.