Post # 1
My first day of my last cycle was Jan 13-16 mY doc said my last cycle was Jan 6 that’s not true my first due DAT was Oct 19 they put my due date at Oct 12 due to my u/s not a big difference but I’m going by my first day of my last cycle and it points to Oct 19
Post # 2
yolonda : go by what the doctor has said and the earlier due date. It might be that you ovulated early and so that’s pushed your dates up. It’s not really about the first day of your cycle once you get to having scans as that is just a rough guess, it’s when you ovulated plus two weeks.
They use a general measurement of a 28 day cycle and ovulation at day 14. That is the standard used for calculations of due date until they do a scan and can be more specific. If you ovulate earlier then day 14 (some people ovulated as early as the day after the last day of their period) or later then those dates will be wrong. An ultra sound is much more specific about dates then your first day of last period.
Post # 3
I’m sort of confused by your post but going by last menstrual period to date a pregnancy can sometimes be wrong. As PP said, the “last menstrual period” method assumes you ovulate on day 14. If you ovulate earlier or later, your due date is actually earlier or later. If your ultrasound was was in the first trimester or early in the second trimester then it is most likely more accurate. If so, October 12 is probably more accurate. Only later ultrasounds (20 weeks+) have more wiggle room and aren’t as reliable indicators of due date.
Post # 4
Due date is based off first ultrasound