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

[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

[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.

[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.

[mummy of 3 boys]

i had a scan at 32wks and it was estimating DS to be 4lb 12oz between then and 37wks 5 days when i had him he jumped to 7lb 15oz

i wouldn't worry

when i was in labour though a midwife checked my tummy and estimated a 3.5kg baby she was spot on he was 3.6kg's!!!

[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

[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

[kungfubecca]

they arn't. too many variables like how much fluid the mum retains.

My GP had a poke around with my last bubs, by feel at 38 weeks and said I rekon this is about a 7lb. She had an extra week to pork up and came out at 7lb 9oz. He was pretty spot on.

[Tegam]

I had a scan at 34weeks with DD2 and was told she was 4kgs i had her two weeks later and she was 3.2kgs. They are normally 10% wrong either way and they can be up to 20% wrong! Just plan for your baby huni. Dont worry about the size. Your body new how to grow it why wouldnt it know how to birth it!

Happy birthing and i cant wait to read your birth story!