Pinkrach I'm afraid I used to think this, however was set straight by Raj Rai and Lesley Regan at their clinic on the matter. Although a Dr (e.g. GP) might use this term, it isn't actually a medically accurate one and has in the past led to women being sent for tests for implantation issues when they don't have them at all, it's an issue which occurs afterwards. If a HPT has shown 'positive' it should be termed 'miscarriage' to avoid this confusion, they told me (and indeed said IVF was the only time you'd 'know' a chemical happened unless you gave yourself blood tests daily).
Indeed Prof Hughes, who discovered Hughes Syndrome blames the haziness about earlier miscarriage as a factor which has delayed many women getting diagnosis in the press.
An additional issue is that chemical Pregnancy is often used, by GPs, as shorthand for "we think it didn't implant properly" and if a HPC has worked, implantation has worked and been in place for approx 48hrs. Thus, although there might not be anything to see on a scan in terms of causes and care it is a miscarriage.
My medical records, simply from my local hospital done by their gynie consultant, list those losses I have had at 5 weeks as "miscarriage, natural, 5 weeks (or in one case 4+6)".
If he hadn't known to do this, as many recurrent miscarriers I know have had, I may have been wrongly tested for implantation/fertility issues.
I met someone who had 'chemical' written 6 times on her records. She had been referred to the wrong people because of this and eventually found her way to the correct clinic after months of heartache and confusion. I was lucky: my local gynie knew better than me (at the time) what to write on my notes so I got seen as quickly as possible by the right consultants.
OP sorry for derailing this thread: BE REASSURED the stuff I have described happens to less than 1% of women and is HIGHLY UNLIKELY to happen to you, and even with that tiny number, most go on to have a healthy child.