Could it be that I have not given up sushi? I was told it being bad for you was an old wives tale.;
I'm sorry, this made me lol. Giving up sushi is a personal decision and it will not cause you to have negative pregnancy tests. I eat a roll here and there an have no qualms about it. My OB agreed that in moderation, it's fine.
I don't know the reason for sure, but I did hear that hcg levels taper off after a few weeks of pregnancy. Lots of people freak when the lines start getting lighter, but it's apparently normal. Call your OB if you're concerned.