There is a lot of wondering that goes on about what happens to those children who die before being baptized. Certainly, many people want to know what becomes of the 4,000 children who are aborted each day in the U.S. and miscarriages are also a sad reality of some peoples’ lives. Catholics believe that baptism wipes away original sin, but what happens when baptism hasn’t happened, does original sin keep the child from God?
The official teaching is that we do not know. The Catechism says:
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" (Mk 10:14; cf. 1 Tim 2:4), 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. (1261 CCC)
We do not know that they are in heaven. If we did, they would all be called saints, but yet we are hopefully optimistic that they are indeed with our Lord and God. We are hopeful that his mercy overcomes the stain of original sin and that they are drawn to his side through his grace.
The teaching of Limbo, where a child spent all eternity separated from God due to original sin, yet not in hell, is no longer held. The Church has recognized more fully the deepness of God’s mercy on all people; especially the unborn. This change reflects an increase in awareness of the Church, not a change in how God treats those who die before baptism.
Continue to pray for them and for the end of abortion, however. We are hopeful, but that doesn’t mean we can lax on this issue. As the later part of paragraph 1261 states: All the more urgent is the Church's call not to prevent little children coming to Christ through the gift of holy Baptism