Giving a gift to
    the wife who gives birth and not to the other wife
Question

                A man has two wives, and it is the
      custom among us that when one of them gives birth, he should give her a gift after she
      finishes her nifaas (post-partum bleeding). Does he have to give a gift to both wives when
      one of the gives birth, or can he give a gift only to the one who has given birth?
Praise be to Allah.The basic principle is that he does not have to give a
    gift to the wife who has not given birth; if she later gives birth, he does not have to
    give a gift to the other wife. Fairness means that he should give them gifts of equal
    value, i.e., if he gives the first wife one hundred when she gives birth, he should give
    his other wife one hundred when she gives birth. He does not have to give her anything
    before she gives birth, but if he is afraid that problems may arise, and he wants to give
    a gift to both wives each time one of them gives birth in order to avoid problems, then
    this is fine and is regarded as kind treatment in the interests of harmony. And Allaah
    knows best.