The Catechism of the Catholic Church states:
1261 “As regards children who have died without Baptism, the Church can only entrust them to the mercy of God, as she does in her funeral rites for them. Indeed, the great mercy of God who desires that all men should be saved, and Jesus’ tenderness toward children which caused him to say: “Let the children come to me, do not hinder them,” allow us to hope that there is a way of salvation for children who have died without Baptism. All the more urgent is the Church’s call not to prevent little children coming to Christ through the gift of holy Baptism.
Perhaps the best way to answer the question is what the International Theological Commission had to say in its address The hope of salvation for infants who die without being baptized:
The conclusion of this study is that there are theological and liturgical reasons to hope that infants who die without baptism may be saved and brought into eternal happiness, even if there is not an explicit teaching on this question found in Revelation”. quoted from the apologist section
It should be noted that this is current teaching and has not always been the case.
- Take* “But the souls of those who depart this life in actual mortal sin, or in original sin alone, go down straightaway to hell to be punished, but with unequal pains”* is a definition from .ECUMENICAL COUNCIL OF FLORENCE (1438-1445). ewtn.com/library/councils/florence.htm
This states 3 things to those who die in original sin alone. a. They are punished,b they go straight to hell c. the punishment is less for those than those who have committed mortal sin. This is not a description of limbo but hell. This is the fate of infants and the aborted.
A second historical teaching of the church is that abortion is wrong because the aborted foetus loses not only its life but it soul “Who will not detest such an abhorrent and evil act, by which are lost not only the bodies but also the souls”? quoted from The Apostolic Constitution “Effraenatam” of Pope Sixtus V against abortionists. This teaching assumes the existence of limbo. (Popes believe in the limbo of the little ones") iteadjmj.com/aborto/eng-prn.html
St Peter and by extension Popes are permitted to change teachings**".I will give you the keys of the kingdom of heaven; whatever you bind on earth will be bound in heaven, and whatever you loose on earth will be loosed in heaven."