norbert:
Strictly speaking theologically, they should go to hell, right, because of the stain of original sin?
The stain of Original sin does indeed seperate us from God, and Salvation. But we must remember that there are Baptisms other than the normal “water” Baptism that we are all familiar with. There is Baptism of Desire as well as of Blood (martyrdom) Wether infants who die previous to birth fall under either of these is speculation. It is, as was stated above, the Catholic position that we leave it up to the Mercy of God.
Original Sin:
newadvent.org/cathen/11312a.htm
Baptism:
newadvent.org/cathen/02258b.htm
Limbo:
newadvent.org/cathen/09256a.htm
From Baptism Link above:
The fate of infants who die without baptism must be briefly considered here.
The Catholic teaching is uncompromising on this point, that all who depart this life without baptism, be it of water, or blood, or desire, are perpetually excluded from the vision of God. This teaching is grounded, as we have seen, on Scripture and tradition, and the decrees of the
Church. Moreover, that those who die in
original sin, without ever having contracted any actual sin, are deprived of the happiness of heaven is stated explicitly in the Confession of Faith of the Eastern Emperor Michael Palæologus, which had been proposed to him by
Pope Clement IV in 1267, and which he accepted in the presence of
Gregory X at the Second Council of Lyons in 1274. The same doctrine is found also in the Decree of Union of the Greeks, in the Bull “Lætentur Caeli” of
Pope Eugene IV, in the Profession of Faith prescribed for the Greeks by
Pope Gregory XIII, and in that authorized for the Orientals by
Urban VIII and
Benedict XIV.
Many Catholic theologians have declared that infants dying without baptism are excluded from the beatific vision; but as to the exact state of these souls in the next world they are not agreed.