I know once we get the BFP we are supposed to stop testing. I've had two losses, though, so that's just not happening. All I do is worry. I have read about the hook effect which says at a certain point hcg levels get so high they in a way overwhelm a test strip and make the line show lighter. I freaked out when I tested yesterday at 7w4d and my line was light. I just knew I was losing this baby too. Today I decided to test the hook effect thinking there's no way that's what's going on. So I took one test (top test) using just urine. So light!!  :( Then I added water so that the sample was nearly half urine-half water and tested (bottom test). Much better!!  :) So if anyone else has been in the same boat and noticed your lines getting lighter it may be the hook effect! Good luck to all you mamas. I'm probably going to throw away my tests now and just wait for my scan at 9 weeks.