Question

Which of the following conditions cause erythroblastosis foetalis?

(1) Both mother and foetus Rh^+ve

(2) Mother Rh^+ve and foetus Rh^–ve

(3) Mother Rh^–ve and foetus Rh^+ve

(4) Both mother and foetus Rh^–ve

Answer 1

Answer (3) Mother Rh^–ve and foetus Rh^+ve

Sol. Option (3) is correct answer because Erythroblastosis foetalis occurs only when foetus is Rh^+ve and mother is Rh^-ve. During I^st delivery, if Rh^+ve foetal blood mixes with mother's blood, antibodies are produced in mother's body against Rh antigen. These antibodies in successive pregnancies cross placental barrier and reach foetus, causing clumping of RBCs in foetus.