This was an interesting bit of information from another board I check in on every now and again (reddit.com/r/tryingforababy)
"Ok so I was using my Googlefu skills yesterday and came across this info on another forum (whattoexpect.com, I believe)... I thought it was incredibly helpful and that lots of ladies here would think so as well!
" hCG doubles every 48 hours. You can have a level of 1 - 5 in a non pregnant state.
Implantation could be later than you think.
If a woman implants at 8dpo, with a 'non pregnant' hCG level of 1 [Which is totally normal] it would rise as follows:
8dpo - 1miu hcg 10dpo - 2miu 12dpo - 4miu 14dpo [Day AF is typically due] - 8miu 16dpo - 16miu
So this lady wouldn't find out until 15dpo on a very sensitive 10miu pregnancy test, superdrug own or possibly asda own. Obviously if she implants LATER than 8dpo [which is normal] she will find out even later.
Now, Take a lady who implants at 8dpo, but has a'Non pregnant' hCG level of 5. Hers looks like this:
8dpo - 5miu 10dpo- 10miu - Could find out here on superdrug own, internet cheapie 12dpo - 20miu - Could find out here with freedom cheapie strip/most poundland tests and asda own] 14dpo - 40miu [day period is typically due] Most tests would pick it up here
So, this lady, even though implantation is on the same say for both ladies, can find out MUCH sooner. Now, If this lady were to implant at 6dpo she could potentially find out at just 8dpo. But if the first lady were to implant at 12dpo, she would find out even later, even if they have the same cycle and OV days!"
So this gives us a better idea of why some of us get BFPs earlier than others, and I think will help people feel less discouraged when they don't get one too early! (Like me with my 10 DPO BFN this morning...)"
I don't know how scientifically accurate it is, but it seemed to make sense to me. It also explains why some people pop out that BFP just about as quickly as they ovulate, and other people don't get their BFP until a week after their period was due.
Anyway, I thought it was interesting information. =)