There's nothing in the Oxford English Dictionary to suggest that sort of meaning. It has in the past been used to mean pregnant, though that's obviously not the case with a 5 or 6 year old.
One nuance, for which the latest example given is 1882, is 'engaging attention' or 'appealing to the emotions'. Perhaps, then, it was used to denote children who seemed particularly pretty, or precocious in some way**? The last newspaper extract, about the Papyruseum, certainly doesn't seem to suggest a child with learning difficulties.
** Edit: or clever girls? Sometimes they haven't been thought worth educating.
I couldn't say whether all this would apply to the 14 year old originally mentioned - at that age and in the wrong environment, pregnancy might be possible.
