So, here's another question for you....Last night at work (I'm a Labor & Delivery nurse), I did a blood test. It was neg, but still no period, and no signs of it coming any time soon. So if the blood test was neg today, than I can be 100% sure I'm not PG? Are there any false neg's with blood testing? The reason I'm a little concerned is we have a scuba diving trip planned next weekend, and if there were any chance whatsoever that I'm PG, I wouldn't go. On the other hand, I dont want to skip it if I dont need to. Any thoughts??? Thanks, guys!!