Idle curiousity really
I am sure (in fact I know for a fact) that I was bigger at this stage with ds (my third) than I am now with my fourth. I carried him very low and all at the front - my bump was enormous by the end but you couldn't really tell I was pg from the back IYSWIM.
This bump is neater and I am carrying much higher - which I think is a little strange because I thought it was all to do with stomach muscles (or lack of) and I certainly haven't been working on them!!