Am I sinful for the death of my fetus after intercourse that occurred at the beginning of the third month of pregnancy, where the doctor mentioned that intercourse is a possible cause for that?

There is no sin on the wife if intercourse is a probable cause of miscarriage. If she takes medicine not known to cause abortion, and it results in a miscarriage, there is no ghurrah (blood money for a fetus) on her. Similarly, if a doctor gives her medicine known not to cause abortion, there is no ghurrah on him. Malik was asked about a pregnant woman who drinks medicine, and her child miscarries. He said: "I see no harm in it, if it is a medicine resembling safety, then there is no harm in it."