I have always used the same measurement for guessing the sex of babies. All belly is almost always a boy and girls sit more in your hips. Don't think I have been wrong yet.
I think that's true too. My son was all belly. Took over my abdomen. My daughter was more compact and higher. Tho she did a number on my body. Lol
My daughter just made me look like I put on weight. I was kind of all over pregnant with her. With my son it was all belly. So maybe there is something to that?