Warning: This is long but worth the read!!

Okay so I needed to occupy my brain during my tww and maybe justify my impossibly early symptoms and I came across some clinically proven research that I just need to share.

First off - there are two types of HCG, regular HCG is the one we typically refer to that is produced by the embryo after implantation has occurred. H-HCG was discovered in 1997 and happens to be:

A) the primary form of HCG present in the first few weeks of pregnancy, and

B) produced by the fertilized egg immediately after conception (before implantation!!).

So, and this is just conjecture on my part, maybe h-hcg is responsible for some of the early pregnancy symptoms we experience.

Anyways, this prompted me to look further into home pregnancy tests and which of these two hormones they are looking for.

So here's what I learned. Many of the newer home pregnancy test do look for both hormones however, they tend to look for the H-HCG at a higher threshold (less sensitivity) than regular HCG. This makes them detect pregnancy later than what is possible.

Of the brands tested in the study I read, Clear Blue Easy was actually the most sensitive brand for regular HCG (6.3 IU/L) and the second most sensitive for H-HCG (25 IU/L). Ladies this means that the dreaded blue dye tests are actually better than first response!! However, if these tests are picking up more on the H-HCG, you may have not implanted yet and that is more than likely the reason for the BFP followed later by BFN and AF. These faint colored lines on clear blue tests are likely not evaps like we all thought.

Anyways, I am hoping this helps ease some of your minds. Baby dust to all of you!

PS here is the link to the study. It is a bit dated but still very interesting. Scroll to bottom for the table of all the tests and their sensitivities (does not include internet strips since its from 2001).

http://www.freepatentsonline.com/article/Clinical-Chemistry/209621723.html