Right or wrong I think this is scientifically very questionable. My understanding is that once you have had a boy a very small trace of the Y chromosome remains present in the mothers bloodstream for a long time \ forever? so surely once you have had one boy or male pregnancy whatever the outcome you could then get a false positive for a boy on using the test in subsequent pregnancies? I wouldn^t touch this witha bargepole. Alos, like they say, it is apparently quite common to start off with twins eg a boy and a girl but for one to be lost very early on, possibly explaining early bleeds. This too would give a false positive as youd pick up the Y chromosome from the lost twin and think the remaining girl was a boy.
I also think 8 weeks is way too early to be thinking about the sex due to the mc risk, presumably anyone tempted to use this would have a specific preference, imagine finding out you had got what you wanted and then subsequently miscarry, why make it harder to bear.
Anyone can request or pay for a CVS at 12 weeks as I did when you can find out the sex anyway (I am not aware of any hospitals that can withold this when giving the genetic determination), surely this is early enough. i appreciate that a blood test is non invasive but this seems like a money making scheme to me.
I read this report in the SUN and it really made me laugh how crap their research was, they stated that it had previously only been possible to find out the sex at 20 weeks and not before, no idea about amnios or cvs, not to mention the fact that modern scanners can see the sex much earlier, you could clearly see the boy bits at my 12 week scan recently, later confirmed by the cvs.