Estimated baby's weight during scan versus actual birth weight

[TransatlanticCityGirl]

I'm wondering how accurate a sonographer's estimate of a baby's weight is during a late pregnancy scan... every single time I hear of a scan being done to estimate the size of the baby it is WAY off and I've heard multiple accounts of women being advised to be induced or have a c section due to babies who are thought to be large, but actually they are several pounds lighter than estimated.

My DD was 9lb 10oz which was a surprise - I was measuring perfectly average so midwife never referred me for a scan. I ended up with an EMCS. I suspect that my 2nd baby will be larger as he was measuring (at both 12 and 20 week scans) to be a week older than is biologically possible.

I'm worried that towards the end of my pregnancy I will be advised to have an ELCS due to baby's potential size and wonder if they will want to estimate via a scan?

Looking to hear what other mothers have experienced before....

Congratulations, terilous

Very happy New Year to you and your expanded family!

Baby was supposed to be small, 5lb 5oz, was born 7lb 7oz so not big but not what I would call small

With DS2, I had a scan estimating him to be 8lbs 9oz. He was born 3 days later at 10lbs 0.5oz. The sonographer told me the estimates could be out by 2lbs either way, and of course they never get feedback so have no clue if their predictions were right!
TBH I don't know why they do them at all seeing as they're so inaccurate.

I had a scan at 41w and baby measured 7lb 6 with 10% margin for error (so max was about 8lb 2).

He was born 5 days later at 9lb 5.

Can't wait for next time

Told by a growth scan at 37+1 that she was around 5lb 2oz, born the next day by EMCS and was 4lb 6oz.... She's now 9 weeks old and 7lb 13oz!

With DC2 scanned at 34 weeks, estimated weight at 34 weeks was 6lb 4oz. Born at 37.5 weeks weighing 8lb 11 oz, which based on 1lb per week estimated growth rate was about right.

So I just thought I'd update this thread (several months after originally posting the question) because as I anticipated, DS was very overdue and we ended up having a scan as I was resisting consultant's advice to induce and we decided to check that fluid, placenta etc all functioning before making a decision. As part of that they also estimated baby's weight.

I was scanned at 41+5 and scan predicted a 9 lbs 8 oz baby, and DS finally arrived at 42+1 at 9 lbs 11 oz!

So in the end, for me anyway, the scan was fairly accurate although several doctors gave me several different points of view regarding the accuracy rate, which can be anything up to +/- 20%!

Anyway he's here now and he's lovely, all 9 lbs 11 oz of him.

I was estimated to have a 7lb baby and he was actually 11lb 9oz so totally wrong. My fundal height was slightly over but nothing concerning so I wasn't sent for extra scans but by the time I gave birth I was huge and people were asking if I was sure it wasn't twins. He carried on putting weight on after birth to the point where they couldn't plot his weight on the percentile charts as they ran out of room on the paper. He was sent to see a consultant as they thought he might have a growth disorder but he was given a clean bill of health. I didn't have GD so that didn't cause his size and Consultant just said very occasionally babies just are big.

Had fortnightly scans throughout, then weekly towards the end. Estimated I had a 12lb'er. 7lb 3oz. Huge amount of fluid, but even that didn't explain the inaccuracy.

I dont think one scan can determine babies weight, you need a series of growth scans to get a picture of how much they gain. my youngest baby dd (now 4 months) gained 2lb every 4 weeks. they predicted 9lb 11oz by the time of my section. she weighed 9lb 10oz at birth (2+2 early too).

I was scanned during early labour. Estimated 9lbs. He was 9lb1oz. Really that should have given me a section as I'm only 5ft. Had been in back to back labour 3 days at that point. Ended up with shoulder dystocia and a crash team and NICU. Still suffer from PTSF a year on.