Question

why is it necessary for people to have their blood examined before marriage?​

Answer 1

I think this is just because...some people have AIDS in them which they think might infect the other person...AIDS is a communicable disease that spreads through person to person sexually or by using infected needles too

Answer 2

to avoid blood incompatibility which arises due to Rh-ve and Rh+ve antibodies.

when the woman is pregnant it  may lead to child's death during parturition

therefore it is important for people to have their blood examined before marriage inorder to avoid such cases