Hello Dr. My Cousin Had An Abortion Recently, This Is

hello dr.
my cousin had an abortion recently, this is her second abortion within a year.
at the time of first pregnancy she suffered from severe pain and when she went to doctor she came to know that she had a stone in kidney and her one fallopian tube also get damaged then doctor suggest her for abortion.
but at the time of second pregnancy she immediately consult to the doctor and all was good at the starting but after sometime she again suffered from severe pain and consult to the doctor, than after whole checkup doctor said that there is no growth of embryo and again she had an abortion.
please tell me the reasons why this happens and the tests and precautionary measures which she has to follow ??