Quoting Squeaky McGee [19 wks]:" <blockquote><b>Quoting mama1821:</b>" do you know what day you ovulated? your lmp is ... [snip!] ... Rule, which is based on the LMP. It may not be what's important, but that's what they go by. It's all just an estimate anyway."
not always, like in my case, the doctors used my ovulation date. there is no other possible day we could have conceived. they adjusted my due date to my ovulation not my lmp. if you do the math you will see what im talking about. my lmp was 9/15/12 and my ovulation date was 10/10/12 and my due date is 7/3/13. your right that most use your lmp but when you have people who are charting cycles and using opk's and ttc, they are willing to listen. all of my ultrasound measurements have been exactly on to the day based off my ovulation date.