The Vatican's International Theological Commission, which advises the Pope, has been meeting in Rome this week to discuss the future of limbo.
It is believed likely to recommend that the concept be dropped as a teaching of the Catholic Church in favour of a belief that pre-embryos, embryos, foetuses and unbaptised babies who die go directly to heaven.
Limbo is also the state/place mentioned in the Apostles' Creed which Jesus is said to have visited between his death and resurrection.
The late Pope John Paul was said to be very unhappy about the understanding of limbo as a place which was neither heaven nor hell but where the unbaptised languished for eternity.
In 1994 the Catechism of the Catholic Church said of children who 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 . . . allow us to hope that there is a way of salvation for children who have died without Baptism."
In his 1995 encyclical Evangelium Vitae (the Gospel of Life), Pope John Paul indicated that aborted embryos and foetuses may be in heaven or limbo.
Addressing women who had abortions, he wrote: ". . .you will also be able to ask forgiveness from your child, who is now living in the Lord."
However in 1905, pope and now St Pius X made a definitive declaration confirming the existence of limbo. "Children who die without baptism go into limbo, where they do not enjoy God, but they do not suffer either, because having original sin, and only that, they do not deserve paradise, but neither hell nor purgatory."
However the statement was not made infallibly.
The belief in limbo is not shared by other Christian denominations, Protestant or Orthodox.
They believe instead that the souls of babies who die before Baptism are immediately in the presence of God.
In the 13th century, St Thomas Aquinas was the first major theologian to speculate that unbaptised infants and others would spend eternity in limbo. It was argued such children could not go to heaven because their original sin had not been erased by Baptism. Yet they had committed no sin and so hardly deserved purgatory, let alone hell.
Limbo also proved a theological solution to the theological problem of where those good people, who lived before Jesus and had no chance of Baptism, went after death.
The name limbo is derived from the Latin word limbus which means "hem" or "edge".