Pope Saint John Paul II and the International Theological Commission addressed this question.
I have always felt as though I have an army of souls of unborn babies supporting me in my work, interceding before God. I pray to them always to obtain the graces I need to do this work of leading souls to Christ and healing. In the beginning, it was just my own son whose presence I felt, but as the years have passed, I know there are millions of souls, a whole army, behind the work, constantly interceding and praying for the healing and reconciliation of their families.
Many, I now know by name. I even pray in front of clinics where I know they have died. It is no longer “babies die here,” but Sally’s baby, Chris, died here, or Tom’s baby, Mary. There is a personal connection to both the child and the parent.
Many argue about the status of the souls of aborted babies. Some think there is no chance that they are in heaven because they have not been baptized. But, like the Holy Innocents, I believe theirs is a baptism of blood and that Our Merciful Savior and His Mother embrace them at their death.
Pope Saint John Paul II tells those who have lost a child to abortion in The Gospel of Life:
I remember the first time I heard those words “nothing is definitively lost,” it stirred up in me a hope of one day being with my child. We are made for heaven, for eternal life with the Lord. Our time here is limited and thanks to His mercy we can reconcile ourselves to Him and to our children.
Years later, the Vatican changed the sentence in no. 99 of The Gospel of Life – the one that had given so much consolation to women grieving over the loss of an unbaptized child, whether through miscarriage, stillbirth or abortion. It seems that theologians thought John Paul had gone too far in stating that unbaptized children were “living in the Lord,” implying that they were in heaven.
This sentence was replaced by one that speaks of God’s mercy and yet leaves open the possibility that unbaptized infants may not be with the Lord: “To the same Father and his mercy you can with sure hope entrust your child.” It’s no small thing to hope in the Father’s mercy, of course, but the thought of even the possibility of eternal separation from one’s child is more than many mothers can bear.
Thankfully, in 2007, Pope Benedict XVI approved a statement by the International Theological Commission (ITC) titled “The Hope of Salvation for Infants who Die without Being Baptized.” Although its endnote no. 98 approves the revised language in The Gospel of Life, the “Hope of Salvation” presents numerous reasons, drawn from Scripture and Tradition, why it is reasonable to hope these children are “living in the Lord.” In addition to the Church revering the Holy Innocents as saints, the Gospels of Matthew and Mark are filled with passages in which Jesus speaks lovingly of innocent children:
LG 11; GS 48, 50).”
In addition, they reason that (1) God’s grace is available to everyone and (2) that God does not ask us to do the impossible:
(Hope of Salvation, no. 82)