So I'm 40 weeks pregnant and ordered the Squeem in my pre pregnancy size.  I just received it yesterday (2 day delivery- Free shipping with my Prime Account- not bad). Anyway, it came in a small box which has a chart that shows what size you should get based on your post pregnancy waist line and your Dress size. I'm 5'5 and picked a 8-10 since I usually run around an 8 pre pregnancy.  Let me tell you... it "looks" very tight.  The material isn't very stretch at all, although it's 75% rubber.  It's supposed to be worn on the smooth side not the rubber side, so if anyone out there is allergic to rubber materials, be sure to wear it on correct side or avoid contact with bare skin.

Besides that, I was hoping to wear it immediately after giving birth, but I see that won't be happening. My belly is about 44 inches now and I doubt I'll be able to fit the tight waist belt until a few months down the road. It is corset shaped, which I do like, but I wish I would've gotten a larger size. I'm thinking an XL or even XXL would have helped but I'm not sure how much I will shrink post delivery just yet.

My order: Size Medium (for size 8-10 dress size pre-pregnancy, or waist size of 29-33 i think it was) according to the package.
My stats are 5'6, medium/athletic frame, currently 44" in waist/40 weeks pregnant.
I'll repost in a few weeks after I've had the baby to see if it even comes around my waist! :-)