Hi Subrata
You'll have to wait till 12 weeks of gestation to do the test,it's done when baby is 12 weeks old in womb,this is what i went through when my second son was born ,you'll have to do the test for genetic mutation also to know whether your other child is effected with thalassemia or not,then comes the HLA,and plus if you think about BMT, you'll have to wait till the donor is two years old,and if you are considering cord blood transplataion,then it's ok, but i don't think cord blood transplantation is available in India,correct me if i am wrong,and please before thinking about BMT,consider the pros and cons of it,as it's a very tough option itself,we have a member here on this forum from Kuwait,Khalifa,whose son went through BMT twice as the first one failed due to GVHD (graft verses host disease). I wish you luck for any decision you make.
ZAINI.
P.S Aren is so cute