I'm reading more and more about people not showing up positive for a hpt for up to two, or even three months of pregnancy. I just want to know how common this is or how many people had this happen to them. I've also herd its possible to show up negative on a doctors blood test and still be pregnant? I just found this out recently and had no idea. How many of you tested negative until finally getting that positive result? Is there anything that can interfere with the results or make it more accurate? (Besides using the morning pee).