For me I had a really sensitive nose before I found out I was pg (which was a big tip off) then I couldn't stomach the smell of meat and it was like that for a few weeks then all of a sudden it didn't worry me as much (first clue). Then I was booked in for a dating scan when I thought that I should be at least 6weeks 2 days and I was so nervous and had a really bad feeling in the pit of my stomach, had the scan and was measuring 5 weeks (no biggy) and no heartbeat which isn't unusal. Came back 3 weeks later and still no heartbeat worst day of my life, but after the first scan I just knew with all my being that it was not going to end well.