Will the fetus lost within the first two months intercede for its mother on the Day of Resurrection, and is there a specific supplication that can be recited for this to be accepted?

The miscarried fetus that will intercede for its mother to enter Paradise is one into which the soul has been breathed, which occurs after 120 days. Any supplication whose conditions are met and whose impediments are removed will be accepted by Allah. Furthermore, any calamities that befall a Muslim expiate their sins, provided there is patience, seeking reward from Allah, and no despair.