According to Mediums when chrildren die at birth, they cross over to the other side and reach
maturity and are raised by the closets relative to the one who gave birth to them, these are called Spirit Children.
They say that often when they become kids on the other side that they play with other children that are living, and usually
only the living kids can see them. They are often called Invisible Playmates or Imaginary Kids. But when living children grow
up they tend to forget about what they saw. There are several books that describe this phenomena like There is no Death
by Florence Marryat, and Birth of Death as a Chang of Perception by Baron Hellenbach.