Yes, I know the Super Pet cages. I have one in my possession at the moment that a friend lent me to transport my sow Charity from her home to mine in. They seem large until you build that first c&c cage then you won't think it is so big anymore. I have 4 sows that live in a 3x4 (just redid their cage yesterday from a 2x5) with a loft for hay.
I don't know alot about piggie pregnancy but I can give you a link to some info that might help you out some. This doesn't tell you exactly when your sow will give birth but it has a lot of very good info.
http://guinealynx.info/breeding.html
Before the babies are born you will want to double grid the cage so the babies cannot slip through the holes. It's easy to do. Make sure to separate any baby boars from mom at 3 weeks as they will get her pregnant and you don't want that.