16w pregnant here and I'm finally admitting defeat to my non-maternity jeans. They'll fit in the morning (with the help of a hair bobbin) but by late afternoon, they're tighter than a rabbits bum 
I've noticed that I have a little bump in the morning but by bedtime, it's a lot bigger. I'm guessing it must be all bloat? It's my 4th pregnancy and I've not experienced this with my previous ones.
It's a pain because maternity jeans are still huuuuge on me, and even going a size up in regular jeans doesn't seem to fit right
Guess I'll have to dig out the leggings.