Erythroblastosis foetalis is caused when fertilization takes place between gametes of
Rh- female and Rh+ male
Erythroblastosisfoetalis is caused when a mother having Rh-blood group conceives a child having Rh+child. This happens when Rh- ovum produced by RH negative motherfertilizes withsperm containingRh+ genes. This is possible only when the father is Rh+.