I've just bought some black 'Leigh' skinny jeans from Topshop's maternity section, they have an elasticated panel at the front that goes across the bump rather than under/over. They don't look like jeans at all and are a very light material, I wore them for work today because they just look like normal trousers.
I lived in Leigh maternity jeans in my first pregnancy, they are very comfy and did me all the way through.
FWIW I had to go up a clothes size from 6 weeks with this pregnancy, I've just bought maternity stuff now at 18 weeks but I've been desperate for them for a few weeks now. Once I'd put them on I wished I'd bought them sooner, definitely no need to be uncomfortable .
I have been spending on maternity clothes today and have seen lots of black trousers!
Seraphine and Vertbaudet both have some in the sales at the moment. I definitely spent too long squeezing into ordinary clothes with the last pg - I want to be comfortable this time! I wore Topshop jeans last time but wished I'd sized up as they got too small.