Which is more accurate for estimating the due date, the day of the last cycle, or the doctor estimating it at the 20 week ultrasound?

Pretty sure it's the ultrasound. Sometimes they'll do one right at the beginning to find out how far along you are, if there is confusion about when you conceived.

With all mine it was the ultresound. It's much more accruate and worth the wait.

Stacey.x

Most definately the ultrasound. Everyone ovulates at different times in the cycle so going by last period isn't always accurate. Its more of a 'general idea' of a due date. Thats why we do 'dating ultrasounds'. Up until a certain point in pregnancy (approx the last month) babies develop at very similar rates, the size therefore lets Drs know at what point they are at, and so when your due date is. Its not uncommon though to come a few days either side of the date they give you. My daughter seemed to need a few extra days 'cooking' before she was ready to come. 6 days in fact. She still likes to take her time with things

When i know i was pregnant i calculated my own due date befor i went to the doctor, by my last cycle, when i went to the doctor and it was the same.,

so does it matter if it was just an ultrasound to tell the gender, and they just happened to tell me that I was a couple days farther along than they thought. Or does it have to be a specific type of ultrasound?
Either way, I guess it doesn't really matter, but I have less than a month to go and I was hoping to have her a little earlier than expected.
But I know I shouldn't get my hopes up since some people go over due, I just want her out so I can see what and who she looks like, and so I don't have to be quite so wierd about everything I put in my mouth, selfish I know, but I really would love some caffiene, and maybe even some fake sugar