Well, as one who subscribes to a "reformed view" of the Gospel, my perspective may not be welcome. Nevertheless, you asked politely (thank you for that) and I shall try to answer honestly and openly.
The Scriptures tell us (Eph. 1) that the elect have been chosen, "...before the foundation of the world." Thus, those babies who are among the elect are with Christ in heaven irrespective of the length of time their earthly existence lasted. If at conception they were miscarried, they were still humans ("formed in the womb" as David says). If they were murdered in an abortion, they were still humans. If they are murdered at 4 years old, 40 years old or whatever, and they are among the elect...they are rescued. The Scriptures tell us in Romans 9 that the choice of election is up to God and, "Before the twins were born, before they did anything good or bad, God said, 'Jacob I will love. Esau I hate.'"
Thus, from this much you can probably gather what I believe will happen to non-elect babies...the same thing that would happen to them if they lived to be 89. Predestination by a loving God is not the same thing as the Muslim view of "fate", although those who recognize it (predestination, that is) are often grouped with that sick, perverted cult of pagan heresy. But, predestination is a Scriptural concept Paul makes clear in Rom. 8.
I certainly share your observation that those who believe in an "age of accountability" or some such add-on doctrine are in a dilemma with this matter. It would incentivize us to murder every child possible to prevent them from reaching the age and choosing poorly.
In the current day reformed view, all things are being managed by God and there is nothing but justice and mercy in Him. Every detail of every life is orchestrated and there are no accidents or early deaths. All occurs just as God designed and is causing to occur (Prov., Rom. 8).
I don't mean this to be offensive, nor provocative. Thanks for asking, my FRiend.
Thanks for your post, it was very insightful.
I certainly believe that God does know the hour of our death and He has known it from the moment of Creation and that means that He has always known that millions would be murdered in the womb. He doesn't condone it, but because He gave man free will He allows it. I don't believe the Catholic and Reformed beliefs differ on this.
I had never really considered the Reformed position that some of the unborn might not be among the elect, but it is certainly true that some of these babies would not have been saved had they lived.
Though I am certainly not a theologian, my personal view is that the aborted babies are martyrs. Murder is certainly sin and as such a tool of Satan. And abortion is the most evil form of murder as it is the only method in which the victim lacks any mean at all of self-defense. The motive for the murder of these children is not anything they have done, it is not based upon anything the children believe, they are being murdered simply because they exist. I believe that Satan has entered the abortionists in the same manner he entered Judas Iscariot and that the abortionists are serving Satan just as Judas did. If this is the case, and I realize I may be incorrect, these babies are all martyrs who have been baptized in blood and are with Christ in Heaven.