Matching blood group before marriage is important This is to prevent Rh incompatibility Rh incompatibility can lead to erythroblastosis fetalis (Hemolytic disease of the newborn-HDN) Fetal RBC gets destroyed & newborn may get severe anaemia, jaundice This jaundice is more severe than Physiological jaundice ( which is the most common and will usually resolve on its own) In very severe form, a fetus may die due to heart failure This is mediated by the antigen-antibodies reaction Transfer of maternal antibodies across the placenta occurs This happens when Rh +ve man marries Rh-ve lady So Rh +ve man should try to avoid marrying Rh-ve lady Matching blood groups for marriage :: Boy : A = Girl : A & AB Boy : B = Girl : B & AB Boy : O = Girl : O, A, B & AB Boy : AB = Girl : AB Boy : Rh+ve = Girl : Rh+ve Boy : Rh-ve = Girl : Rh+ve & Rh-ve Blood groups that do not match for marriage :: Boy : A = Girl : O & B Boy : B = Girl : O & A Boy : AB = Girl : O, A & B Boy : Rh+ve = Girl : Rh-ve