I wear mine. I felt self conscious until I got used to it, and I think the main reason to wear it is so people who will offer a seat, can offer with confidence ie def know you are pregnant and not just bloated. So, if you do find you need a seat at the moment you should definitely wear it. Sitting down when you need to is better than feeling faint and crappy or worse actually collapsing. If i dont ask, I tend to get a seat on the tube about 80% of the time I reckon. The train almost always, the bus almost never!!!