Is it permissible for a pregnant woman to discontinue a prescribed stabilizing treatment, given that there is a hormonal cyst that may disappear on its own, and that the treatment is not for the cyst, and that discontinuing the treatment may lead to miscarriage?

It is not permissible to abandon the prescribed medication for a pregnant woman, because it protects the fetus from miscarriage. Causing the expulsion of the embryo after its establishment in the womb is considered forbidden by a group of scholars even before the ensoulment. It is unanimously forbidden if it is after the ensoulment without necessity.