Exactly what I wanted! They fit great and seem like they would be good for almost all trimesters. The part that covers the belly is soft and stretchy. They are very comfortable and I'm sure I'll keep wearing them postpartum. I bought the M and I am 5'4" and 160 lbs and currently 6 months pregnant.
I'm only in my second trimester, so I'm not sure how they'll fit as I progress through my third. However, for now, these are amazing! They are rather opaque without being like leggings, they stay up, and they're a perfect length. I'm 5'1" and was a size 6-8 pre-pregnancy. I got the size 1. I recommend!