I know what you are talking about. When I was pregnant with DD I always had mints/tic tacs on hand as I always had a yucky taste and was always paranoid that I had smelly breath. I don' t really know what stops it though. I found it to be worst after a cup of tea.
I had it early in this pregnancy to but it seems to have gone for now, I am sure it will return though.
I know it is horrible but I assure you once bub is here it will go .