I was taught there are different forms of baptism. First is by water the most common. Second is by blood (Martyrdom)and abortion IS Martyrdom. Third is by desire, you want to be baptized but die before you can be.
I have thought that if the Church were to plead to God that all those who die before birth be accepted as members of the Church, this ought to have effect. At least celebrate the rite of Christian burial for these anonymous souls.