Do spirits of aborted fetuses become earthbound and need rescuing?

This does not happen except in very late-stage abortions. If the abortion takes place before the third trimester, the actual soul is not yet on board and residing within the physical form of the fetus. It is only after the so-called quickening that the soul entry has occurred to a significant degree, and then is completed with the act of birth. So in that late stage, whether through a partial-birth abortion for example, or a spontaneous abortion of a late stage pregnancy, there may well become an earthbound consequence for the emerging spirit in making its transition, and there are many such beings in limbo for this reason.