They're clearly designed to make women obsessive about becoming pregnant - and with ever increasing promises of an accurate result three, four, five days before your period is even due their aim is clearly just to cause stress and to make yet more money for the manufacturers.
Ultimately, if you're pregnant you will still be pregnant if you test a couple of weeks later, and if you're having a chemical pregnancy, is there really any need to know? I'm not talking about a full-on miscarriage - of course I'm not, but where the embrio simply doesn't implant but is picked up because of some uber sensitive test, isn't that just adding to the whole stress that is ttc?
When I rule the world I will ban them, and only allow pg tests that are accurate from two weeks after a period is due... 