Yes, I would expect that to be fine. Growing bunnies, pregnant does, and nursing does have similar nutritional needs. You could check the label-- it might even mention pregnant or nursing rabbits too.
I don't know how fast she will eat the pellets, so I don't know what size bag would be good...
Basics for pregnant rabbits:
--she needs plenty of protein. That means either alfalfa-based pellets, or access to alfalfa hay, or both. It should be fine to offer other hay as well, and anything else you would normally feed a rabbit. Always keep water available.
--make sure she has a nestbox to...