I had pretty much always worn Gap jeans - I think their "always skinny" fit is a great approximation of a higher-end jean at a more reasonable point (around $60 full price.) The denim is thick and soft, and their washes never look cheap.
I know that a lot of pregnant chicks swear by the "rubber band through the zipper hole + belly band" equation, but I could just never wrap my head around the idea of walking around with my pants undone the entire day. No thanks. After I had worn the 5 or 6 flowy dresses I own about three weeks in a row on rotation, I figured it was time to take the plunge and buy some new pants. I went into Gap and was pleasantly surprised - their demi panel option (a wide elastic band that sits below the bump) was a perfect fit. I bought the size I was before pregnancy - that's right, don't go up a size, they stretch out in all the right places. I've also washed and dried them in the machine, and they're great afterwards. I'd actually recommend it, it helps them keep their shape.
When trolling around at the beginning of my pregnancy getting an idea for what I'd need to buy, I read the most positive reviews about J Brand maternity jeans. A friend of mine even asked me if my Gap jeans were J. Brand - inspiring this post. I'll admit, I haven't tried any of their styles on - $218 just seems a little nuts for jeans to me, maternity or not. If you have, leave a comment and tell me if I'm wrong! If you're like me, and love Gap's jeans pregnant or not, you can head on over to their site. FYI, they pretty much run amazing sales the entire month of December, so while there isn't one today keep checking.
*ps: i wasn't compensated for this post at all. i have just really loved gap's jeans since i've been pregnant