I used a 2X3 softbox slightly behind the subject to achive the 'rim' lighting. There is also an umbrella on the right side behind a bit also. This created a bit of bounce reflection from the white walls which washed the dark areas to give just a bit of detail in the shadows.
Thanks! I think posing for maternity is much harder than for portraiture because there are not a lot of ways of shooting this that hasn't been done to death! I'm always looking for a new way to show something. Lighting is certainly one way of doing that.