Preggibellies run classes for pregnant and post-natal women. I have been to lots of their classes in Sydney and Melbourne. The classes can be great, though the experience really turns on your instructor. A couple of instructors I had were a bit too low key for me and I didnt' get enough of a work out, but most instructors are really good. They have heaps of locations so it's pretty easy to find a time and location that suits, and an instructor that suits too. Value seems pretty decent. Don't have to bring anything apart from water. The website and their office staff make it easy to book and cancel classes.