measurements for dating...

[mhaddon]

How accurate is an u/s based measurement for dating? I had one done at what I thought was 13 weeks and it put me back to 11 weeks. 2 weeks off seems a lot to me... It was my first pp af so could that account as to why it was so off? I mean ovulation would have been when I should have another af according to the dates... it just seems odd to me and wondered if anyone had experience w/ this as well.

[OneFabMama]

I am not help. I have heard earlier ultrasounds are pretty accurate as far as dates go.

At my very first ultrasound I was just 6 weeks, I think. I measured 5.5 weeks/no baby seen. Had another at almost 8 weeks. Measured exactly that. Had another at 13 weeks 6 days. I measured exactly 13w6d. I had my 3d US yesterday at exactly 24 weeks. He measured exactly 24 weeks. LOL

BUT, according to my LMP I should be a few days behind what the US says. *shrug* I dunno. It confuses. I've had like 4 different due dates all within 4 days of each other.

Sooooooo, I am of no help at all. 2 weeks seems like a long time, but with a US at 13 weeks you could probably go 2 weeks in either direction.

[babyholic]

I know that early U/S are usually more accurate than later ones. I just had my first at 26w6d and the baby measured 27 weeks. The more U/S you have, the more likely you will have multiple due dates and confusion. Especially if it's a different person doing the U/S each time.

I would take the U/S due date for what it is, (an estimate!) and not be too stuck on the number.

The reason it's more accurate in early U/S, is because they guess the length of pregnancy by the stage of development the fetus is at. It gets less accurate when the body is fully developed and baby is just putting on fat.

[keegans_mommy]

I looked that up with my first u/s and from what I found, they are very reliable. For me that was true also. I charted and got my due date from when I ovulated and so when I went in for that 8 week u/s it was 2 days off from there only so that hit fairly good

Now, the later in the PG, I wouldn't look too far into that because right now this baby is measuring close to 2 weeks ahead! I just have big babies

[mhaddon]

Thanks!

[sunnymw]

My old OB told me at the time of my u/s that early u/s is plus or minus 1 week, and anything past the first trimester is plus or minus 2 weeks. Weight is also plus or minus 2 pounds. Not too accurate if you ask me

[ShayneLeMaster]

im not much help on this one... all of mine were pretty right on...

with this preg they " upped" me a day at my 20ish week u/s .. but his weight estimate had him "large" for dates.. soooo... however they come up with that stuff..

[spiritbear_momma]

With all my 4 pregos,,this being my 5th baby but 4th pregnancy,,,i seem ed to measure a few weeks bigger then dates ,,,but never really showed on outside,,,my U/S seemd mostly accurate by dates but baby was either way bigger or smaller,,so i guess really an estimate as one momma said,,they induced us 2 weeks early with myDS 2006, they said close 10 lbs at 36 weeks,,,,well he only weighed 7lb12.5oz,,,,,there was so much water if scared even the OB,,she jumped back and our maternity dr,,,,kind of chuckled and said oh maybe we should not have panicked,,,,lol was all super good our lil guy arrived safe,,,

[mother_04_07]

"normal" ultrasounds are plus or minus 2 weeks


a EARLY level II (2) ultrasound *High risk mothers* can be accurate as 72 to 90 hours of age