How accurate are weight predictions via ultrasound?

[krystals]

Just wondering what people's experiences have been with accuracy of weight predictions from Ultrasound.

I'm 32 weeks and had an ultrasound earlier this week after some bleeding. Everything is apparently fine (Yay!) and bubs is measuring 34-35 weeks and approx 5lbs

How accurate would this measurement be? Should I start preparing for a whopper?

[*Beema*]

It depends very much on how detailed they do the US.

Some just do a measurement of the Femur and a couple of other minor measurements and these estiamtes can be out by quite a bit.

We have had some done where they take a lot of mesurements around the abdomen, head, limb lengths and diameters etc, to this detail the weight is a lot more accurate, but never perfect

I wouldn't worry too much yet because a lot of people have been told they are having a big bub and a little bubba comes out!
Take care and glad that everything was ok after your bleed

[skybie]

my experience with them hasnt been positive.
with DD2 i had a growth scan 2 days before she was born and they told me she was behind for dates.
she was born 2 days later (4 weeks early) and was 7pd 8 (3550gms) and was 50cms long. i fail to see how that is behind for dates!!!
i wouldnt worry to much about a big bubba. the only time they can tell how much they weigh is when theyre actually here!
Good luck

[meow]

I wouldn't worry too much yet because a lot of people have been told they are having a big bub and a little bubba comes out!

Yep and also- why does a big baby matter? Their heads moosh up to fit through and head sizes barely vary regardless of overall weight anyway so it's pretty much a moot point. You can birth this baby no matter the size

[Rowellen]

I was told that my bub would be around 7lb but he was 9lb10. I wouldn't worry about birthing a big bubba - I'm 4'11" & had a drug-free vaginal birth no problem. I've also heard of people being told they'd have a big baby but birthed a little one. I'm glad everything's fine now.

[krystals]

Oh, Meow, I'm not worried about a big bubba! I'm very happy that he's a good size already, particularly if he's born early Thanks for the encouragement about getting him out though!

We had a pretty detailed scan from what I could tell, everything was measured a couple of times and they didn't seem to leave anything unchecked. Was very reassuring to see that everything was fine!

Really appreciate the feedback!

[Trillian]

Take any guess as to bub's size with a grain of salt. It is impossible to accurately guess, so if they happen to get it right, it's sheer luck really. Knowing that bubs is growing well is all you need to concern yourself with

[teresa]

i was told at 34+2 weeks that DS was measuring at 40+ weeks and over 3.5kg. he was born the next day weighing 2.7kg. its only a guestimate and very rarely right

[Jaycee]

For me it was very accurate. 3 days before i was induced i had a growth scan and they told me bubs was 6lb 6oz, when he was born he was 6lb 5oz.

[*LovemyKids*]

Krystals i had an ultrasound today and they told me that bubs rough weight was also 5 pound i am not overally worried but i suppose if we prepare ourselves for big babies we should be right!!! Goodluck and sounds like our babies have similar ideas!!!!! Take care talk soon

[Lenny]

I don't know if there is any actual data on this. I'd be interested to read it.
Both my babies were apparently average to start with, then as time went on they apparently got smaller (or didn't grow much) according to the ultrasounds.
Despite these predictions DS1 was born 7'11 and DS2 was almost the same. Very average, and not what the scans were reading.

[August]

When I was pregnant with my first, an ultrasound in my 35th week predicted the his weight to be 5lb 12oz. DS was born 36+2 weeks and he weighed 5lb 12oz. (He was to be born early due to a medical condition). So it was pretty much spot on in our case!

[OceanPrincess]

Way inaccurate in my case - had a scan at 32wks and was told she was already over 3kg, to expect a big bubba as they can put on 250g a week in the last few weeks

DD was born at close to 40wks and she was only 3.7kg.

Putting on less than 700g in 8wks is highly unlikely... considering all they do in the last few weeks is gain weight, so it was very inaccurate.

[Traveller]

I had a scan 3 days before labout with DS2, predicted weight 7lb, actual weight 8lb 2oz. My sister decided against a VBAC because of a predicted weight of over 10lb (and I know that's not really a reason not to VBAC but she has it in her head she cannot birth a big baby as she is so slim) and her daughter was born weighing 8lb 2oz a couple of days later.

I's so interesting to see other people's experiences of inaccurate weight estimates.

[KimB]

My 4th I was told she was going to be over 10lb but she was only 8lb 4oz. I was freaking out because of the size she was supposed to be that I opted for an induction early but shouldn't have worried. I had a natural birth with gas. My others they never said what they were going to be lol

[sas85]

At 34 weeks they told me DD2 was 2.5kg so spot on the 50th % - well 6 weeks later DD2 was born at 2.96kg (more like the 10th %) so either it was way out, or she gained under 500g in 6 weeks which is I suppose possible as I don't feel my tummy got much bigger.

[carr2walks]

I had a scan with my son at 36w 4days and he was approx 3.6kg. We had him by c-section (planned) at 38w 4d because every time my Ob scanned me she could tell he was growing VERY fast, plus my BP was up. He came out 4.154kg andI was told there was no way I could of had him naturally as his head was already stuck in my pelvis.
Good luck!! Big babies are great!! He was in 000 by the time he was 3 weeks old...hehe...fatty bumba!

[appletree]

I had a growth scan at 36 weeks for DS where they said he was already 4kgs, he was born 4 weeks later at 4.62kgs, so i am guessing it was fairly accurate.

At the time i chose to believe it was inaccurate + or - 10%, and tried to convince myself that he was no more than 3.6kgs. The hospital still managed to unnecessarily try to scare the cr@p out of me with this info and then to try to talk me out of a VBAC.