At our last visit we heard the HB at 182. We were 10 weeks 3 days. I asked the doctor if we could breathe a lot easier and she said "Not a lot but easier." I asked her when we were in the clear and she said 13 weeks. However, after hearing two strong HB's three weeks apart I am not worried any more. I think you're fine after hearing it three weeks in a row. I've heard from other women on babycenter.com that their doctors told them after 9 weeks the chance of miscarriage goes down to 3-5% after you hear a HB. I hope that makes you feel some better even though it wasn't so helpful.
I'm looking for what others have heard from the doctors and experienced themselves...not something from about.com. I've seen lots of different information from the internet and it is so varied. Thanks, though.
miscarriage.about.com/od/pregnancyafterloss/f/oddsheartbeat.htm