What's more accurate?...?

Question

...my last menstrual period or the ultrasound? My lmp was on October 23, 2006, but had two ultrasounds done and said that my lmp was on November 5. I'm positive that my lmp was in October because i remember my last period was two days before my 18th birthday. The doctors said that I probably forgot and gave them the wrong date.. but i know i didn't.. So since they go by the ultrasound, the doctors pushed my due date two weeks forward.. instead of Aug. 1, it's Aug. 12.. i thought that due dates are calculated from your lmp? why do they now calculate it by how the baby is growing from the ultrasound? Has anyone experienced this? Which due date is the correct one... the one from your lmp? or the ultrasound?

Answer 1

Ultrasound is more accurate at 22 weeks pregnant. (fetal age 20 weeks)
The baby is about 11 inches (28cm) long (crown to heel) and weighs in at about 1 pound (450g).

But you know your dates, so take your pick....

First Day of Last Menstrual Period:November 5, 2006
Probable Date of Ovulation: November 19, 2006
Possible Dates of Conception: November 16 to November 24, 2006
Due Date: August 12, 2007 (40 weeks)

LMP on October 23, 2006 Cycle: 28 days
Possible Dates of Conception: November 3, 2006 to November 11, 2006 Due date: July 30, 2007

Answer 2

If the ultrasound was done early in pregnancy--before 12 weeks then the ultrasound dating is very accurate. Later in pregnancy it can be off up to a week or more. The most likely thing that happened is--you DID get your period Oct. 23, but you ovulated later than is textbook. Doctors assume a textbook 28 day cycle with ovulation on day 14--you just ovulated a bit later.

Answer 3

I'd say the date from your lmp would be the more accurate one, but remember that 40 weeks is just an AVERAGE pregnancy anyway, so the date you give birth could be anywhere from to weeks before to two weeks after that and still be considered normal. :)

Answer 4

The truth is the due date is more of a guess anyway since you can never tell when your children will come. my son came over 2 weeks before his due date and my daughter came 3 days before her due date. I would say that the Imp would be more likely since they said my daughter was smaller then she should be. But in the end my due date to start with was right. But you never know. They will come when want to come. Sorry I couldn't help more.