Hello, I have gone through your query and understood the concern. The medication prescribed to treat your renal stones has been categorized under C by the FDA during pregnancy. This means animal studies have shown unwanted effects while there are no adequate human studies. Thus, the use of this medication is warranted only if absolutely needed. Nevertheless, it cannot be said that the use of this medication may have caused the missed pregnancy. It is true that stress and trauma can lead to an abortion. Other possible causes like hormone insufficiency, genetic defects, infections etc., also should be excluded. A postmortem performed on the abortus can help to know the cause and help planning future pregnancies. Hope this helps.