Here is a verse that can indicate that babies and young children will be in heaven:
Deuteronomy 1:39 Moreover your little ones, which ye said should be a prey, and your children, which in that day had no knowledge between good and evil, they shall go in thither, and unto them will I give it, and they shall possess it (the land)
The earthly country of Canaan was to be a symbol of heaven that we will inherit. The adults who knowingly sinned against God were not allowed to enter the land, but their children, who did not know right from wrong, were able to enter it.
This not only goes for babies and children, but even adults who have never heard the gospel of Jesus Christ or who have never seen a Bible, but have lived up to the small amount of truth that has been given to them, then they will be saved also. God is a just a fair God, the only perfect judge. We must ultimately trust in His righteous judgment, and not our faulty judgment.
hope this helped.