ultrasound weight accurate?

ShianeNicole · October 2015

Hi ladies!
I'm a FTM and just wondering how accurate the ultrasound weight is? According to "The Bump" video, our little girl should be 6 pounds. Well yesterday at our ultrasound, the tech said she was 4lbs 13oz. The only thing she said is "well she's not huge... " and kinda just stared at the screen. We're meeting with the doctor this coming week, and the tech couldn't really answer any of our questions, she kept saying we will talk to the doctor. It really just freaked me out. Hoping to not drive myself crazy for the next few days. Any experience with this would help, thanks girls!

BowWowBowie · October 2015

It can be off by 2 pounds either way. Don't fret, your LO could just be little!

MoRay05 · October 2015

My LO was measuring big for most of my pregnancy then measured small for a few weeks. I had another ultrasound earlier this week and he had a growth spurt and is now right on track. I asked the tech how accurate it is and she said it can be off by 10% either way.

dramaphile · October 2015

Recent studies have shown that ultrasound measurement is less accurate than fundal height measurement and either can be off by a pound or more. I've had a few friends whose babies were measured small or large and ended up being off by over a pound.

msjudithk · October 2015

Ultrasound weight is just an estimate. They told me my LO is a little larger. But, you never know until they come out!
Don't worry - if she is a little smaller you can enjoy all the cute clothes longer!

ahowell88 · October 2015

I've found them to be pretty inaccurate in my personal experience. With DS1, they were sure he would be over 8lbs (an ultrasound done one day before his delivery) and he was 7lb 4oz. With DS2, they said he would probably be around the same size as his brother and he ended up being barely 6lbs, the ultrasound being done the same day he was born.

ktcheramie · October 2015

I am a first time Mom too.. I don't know much about the ultrasound being off on the weight of a baby but I do know that a small baby who is active and happy is perfectly healthy even if they are on the smaller size. Currently 36wks, but at 35wks my baby boy was weighing 4.5lbs and although my Dr. seemed a bit concerned at first after being put on the monitor and doing extensive ultrasounds on his brain, heart, and lungs and it all showing he's perfectly healthy. She explained to me that bc I was a petite framed woman and have never abused drugs or anything like that then a smaller baby is common and healthy. And bc he is moving and kicking all the time like crazy it also shows that he is perfectly healthy. Also. It could be just genetics and she would worry more if he wasn't so active. But because of his weight it looks like I'll be induced early at 38wks if I have not fallen into labor myself before then(was 2cm dialated and 95% effaced last time they checked my cervix)
Goodluck with everything and try to stay positive! Sending my thoughts and prayers bc I know how scary it can be! And you never know, I have a friend who was born 4.3lbs and now he's 250lbs standing at 6ft3inches, would never know he was born so tiny, however, his mom was also a petite woman, so if you're petite too, that could just be what it is.
Don't fret, wait to see what your Dr. says and keep the positive thoughts for a healthy and happy baby!!

Pontot31 · October 2015

It's really just a guess.
Also 6lbs is average. But someone's got to be above or below that to get that average. Your baby doesn't sound too small at all.

lakesideknitter · October 2015

ShianeNicole said:
Hi ladies!
I'm a FTM and just wondering how accurate the ultrasound weight is? According to "The Bump" video, our little girl should be 6 pounds. Well yesterday at our ultrasound, the tech said she was 4lbs 13oz. The only thing she said is "well she's not huge... " and kinda just stared at the screen. We're meeting with the doctor this coming week, and the tech couldn't really answer any of our questions, she kept saying we will talk to the doctor. It really just freaked me out. Hoping to not drive myself crazy for the next few days. Any experience with this would help, thanks girls!

As pp's have said, ultrasound weight estimates are notoriously inaccurate and some babies are just small. I was born a week overdue and weighed barely 6 pounds with zero problems. Try not to worry.

nano1 · October 2015

Both my kids were within 1lb of the latest ultrasound I had before delivery.

angelinthepit23 · October 2015

At my growth scan LO was a little over 5 lbs. Tech said it could be off anywhere from 1-2 lbs.

JLW0504 · October 2015

DD1 was measuring at 12-14 lbs at her last ultrasound. She was born 8 lbs 14 oz.

DD2 measured 6lbs 15 oz at her last ultrasound and she was born 6lbs 6oz.

Ultrasounds are an estimate. I don't put too much stock in them as far as weight measurement goes.

Ashleyw · October 2015

I wouldn't stress, if your LO is super low it is very hard to measure. With my first, twins, baby A was so low they had a hard time measuring him said he was only 3lbs and b was 6-7. When the boys came out they were both almost exactly 6 lbs

ShianeNicole · October 2015

Thanks everyone! I am very petite, so maybe she will just take after me. We do a biophysical ultrasound every week and two NST sessions and she passes everytime with flying colors. Very active! I really do hope she beefs up, I've still got some time! Thank you for all the positive thoughts and responses

CayceFry · October 2015

My midwife hasn't mentioned how big baby is AT ALL just that my fundal is measuring on target. I have only had 2 ultrasounds way back. I guess it will all just be one big surprise!

AmoLovesAud · October 2015

They told my SIL that her kid would be on the smaller side (so assuming 6lbs is average, that or smaller), he was just shy of 10lbs. They're not good with guessing baby weight.

stephmoburke · October 2015

With my first, they told me that he was almost 9lbs and he was 6lbs 11oz. With my second, I had an issue with my placenta and in turn, our daughter wasn't getting enough nutrients and the ultrasound tech said that she was just over 3lbs the day before I was induced. She was 5lbs 10oz. It's just an estimate. I'll be 38 weeks on Monday and didn't even pay attention to the weight they have me at my ultrasound because I was so excited that he was healthy and waving at us

poupoule · October 2015

CayceFry said:

My midwife hasn't mentioned how big baby is AT ALL just that my fundal is measuring on target. I have only had 2 ultrasounds way back. I guess it will all just be one big surprise!

Same for me !

NathanheartsKim · October 2015

All my midwife has said is she "thinks" this one might be bigger than my first(7lb6oz) but smaller than my second(8lb12oz). Lol

tyrannis · October 2015

Hope not that accurate. Ftm here I'm 36 weeks and according to ultrasound my baby is 8 lbs already. Doctor said there will be alot of people when I deliver just to make sure baby doesn't get stuck or something.

urby87 · November 2015

My LO was measuring 19th percentile - about 5 lbs 11 oz - according to the ultrasound at 37w to confirm breech positioning. Haven't gotten another weight estimate since then, but we have had two more ultrasounds since (one to re-confirm breech, and another before an attempted version), and they were still saying "small." I guess we'll see tomorrow!

WeirdAlice · November 2015

An estimate. They were off by a minimum of 5lbs with DD1.
Said she was no less than 11lbs and she was 6lbs 7oz.

savyjohn1 · November 2015

I was told 12 oz give or take at my last ultrasound. I think it is all educated guess work, as you just don't know until they are out! The best thing to remember is are they growing?? If yes - don't sweat it so much!! it will all be ok! I have been told to expect another big baby - so here we go!!!

urby87 · November 2015

WeirdAlice said:

An estimate. They were off by a minimum of 5lbs with DD1. Said she was no less than 11lbs and she was 6lbs 7oz.

5 lbs?! That's outrageous.

joforyoga · November 2015

I've been told it's an estimate within a pound or so? I'm 40 weeks and my baby is measuring at 6.8 pounds. My midwife showed me the graph they use and this is the low end within normal for 40 weeks. I think it depends on how the growth has progressed as well. My baby has been moving lots and growing consistently so they are not concerned. It might be different if baby has been on the higher end of normal as a "big" baby throughout the whole
Pregnancy and then it changed all of the sudden. I think as long as iltrasounds are normal and baby is still getting nutrients from placenta then all is good. Consider your size as well. My starting weight was 104 so I'm pretty petite and so is my husband so they didn't expect a big baby.

riott1977 · November 2015

My daughter measured 4 pounds 11 ounces at 35 weeks which is a little small, but not under the 10% that would cause alarm in any way, then at 38 weeks she measured 6 pounds 9 ounces, which is much bigger and more towards the middle range. So they can gain at odd intervals as well. And the ultrasound weights are only estimates, so it can be off either way.

arwestover3 · November 2015

With my first, they told me she was huge; she was 7 lbs 5 oz. This second one was measuring small on ultrasound and fundal height; she was 8 lb 9 oz. It's all totally guesswork!

Sballerina · November 2015

On Wednesday I had an ultrasound/biophysical profile done in order to check on baby since I am past 41 weeks. When the technician finished, she said she was going to have one of the doctors meet with me because the ultrasound showed low amniotic fluid. I had already gone over the nonstress test with a different doctor earlier that morning. Once the second doctor did see me, he said the ultrasound showed low normal numbers, but that he would not be surprised if he did a check himself it would show completely normal fluid amount.

He explained that each ultrasound tech has their own quirks. Trends essentially. He said the tech that checked me consistently gives low amniotic fluid readings. He joked he should make her buy him lunch for underestimating mine! And he said he has another tech that consistently gives "small baby" readings.

Basically it seems ultrasound readings may be almost as much art as science. They can show us valuable, potentially life-saving information. However, when dealing with low risk pregnancies, the normal margin of error when it comes to ultrasounds may prove to raise concerns that are ultimately unnecessary. My husband and I spent half an hour wondering if the results were concerning enough to induce sooner, or whether we are fine continuing to wait for spontaneous labor. Once we met with the doctor, he was so confident about the completely normal amd healthy amount of fluid that he said it was not even necessary to get another NST before the weekend!

Ceridwen77 · November 2015

Had an ultrasound yesterday and the estimated weight is 8lb 8 oz @ 39w 4d. Hoping this measurement is off! Or kiddo makes an appearance soon.

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