i keep catching my daughter eating cardboard, she eats it in bed so i don't make her throw it away, it use to be paper now it's card board its driving me crazy
She might be pulling your leg or have a condition called pica where people have a craving for nonedible items like paint, clay, and dirt.
Like you said this is sometimes seen in pregnant women but it is also common in children.
It is not known if pica is caused by a lack of something or if the pica causes the defenicy.
In any case if this continues she needs to see a doctor before she causes damage to herself.