I would house them in something else other than that cage after the babies are born...

mom rats love to pile bedding into corners, building them up... babies could spill over and out... and even when they get older, you dont want them finding thier way out through the bars, the drop may be enough to hurt or kill one at worst.

From my experience, babies dont seem to have a good depth perception early on, and may just jump.



Side Note: Ever try putting a rat on a bare glass table? If it has any wood they can get to in the edges or middle, they will walk on that rather than the glass.