How can I find the reason behind my 2 abortions - #9615

I have my first abortion on 7th month and 2nd one on 3rd month in first pregnancy they said it was due to infection, and in second pregnancy the baby hadn't formed, I don't know why this happening when I ask the doctors what should be the infection would be ,no we can't find what the infection is. A doctor said you've sinus issue , another doctor said you've skin allergy may be it is also a cause