The tank is new, and just water from the established tank isnt going to help. I would leave her as is. As stated above, it can cause her to loose the fry, stress drop (early birth) and possibly die. I would leave her in the tank, and add plants for the fry to hide in if she does give birth.
I have to agree here... just make sure the fry have many plants/places to hide and they will do well for themselves. It seems best to me not to stress the mother out.