Was the death of the fetus caused by the Ruqyah Shariah (Islamic exorcism/healing)? And is it obligatory to fast two months as expiation for that?

The lawful ruqyah (incantation) by means of the Qur'an and Sunnah does not cause harm; rather, it is beneficial by Allah's permission, and it is not a cause for the death of the fetus. It is beneficial in repelling and removing afflictions, so continue to perform ruqyah on yourself with the reported supplications and remembrances. What happened is by Allah's decree and destiny, and the lawful ruqyah has no connection to any of that. Allah, the Almighty, said: "Say, 'It is for those who have believed, guidance and cure,'" and "And We send down of the Qur'an that which is healing and mercy for the believers." There is no blame upon you for the death of the fetus, and you will be rewarded for your patience.