Jenna, I changed mine yesterday, as was showing me 4 or 5 days behind, and I knew I was 13 weeks today and I wanted to see it in black and white, or green and brown, haha! It's not bad luck, it's just a countdown to how soon you'll be holding your baby!! And thats from me, the craziest most worried superstitious one out there!! I can't even go to sleep or leave for work for the day until my oh kisses my belly 3 times and the kisses me 3 times, as convinced myself if he doesn't then something bad will happen, Yes I am crazy!x