[Zoggite]

I see what you mean, Titch- UPSI did occur in the most fertile ('risky') period of cycle, but I meant that EHC had been taken within 72 hours of UPSI, which is when it's supposed to be the most effective- as opposed to 6-7 days after UPSI;
While we're on the subject of reliability of pregnancy tests: I was taught at uni in Belgium that doing a test too soon could mislead women who were trying for a baby, as "false positives" were common: apparently, a third of all fertilised eggs are spontaneously aborted before the 3rd week and therefore go undetected, the bleeding being mistaken for a "normal" menstruation, and had the woman not taken a pregnancy test, she would never have known that she had been pregnant technically for 2 weeks...
Once the 18th-19th day after conception has been reached, the risk of spontaneous abortion drops a lot, so a positive test then is more reliable...
Has anyone else heard of this reasoning?