In certain cases doctors advise that the foetus is so deformed that it could be very difficult to treat the…

In certain cases doctors advise that the foetus is so deformed that it could be very difficult to treat the born baby and, perhaps, it (the child) would live a very short time suffering pain and agony with his parents, then dies. Is it permissible for the would be mother to abort the foetus? Also, is there any difference between the foetus with a spirit and that which the spirit has not yet entered into yet? Assuming it is permissible, should compensation [or blood money] be payable? Who should pay it?