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How accurate are 30+ scans to predict baby's weight?

(29 Posts)
aclxxx Wed 02-Apr-14 20:38:25

I had my 31 week scan today. All is well which I am grateful. However the lovely sonographer said baby's weight is average. Me: good, what is the weight of baby? Sonographer: nearly 4lb.
Ouch, I have 9 weeks to go, I then asked the estimated delivery weight, I am told 8-9lb grin.

I am hoping for some encouraging experiences or any tips!

This is DC2, first DC arrived via CS due to breech presentation. I have been given option for CS but have not decided.. I do want to try VBAC. But thinking of the weight is bringing tear to my eyes!

Thank you in advance for reading

Raxacoricofallapatorius Wed 02-Apr-14 20:42:01

Not very accurate at all. grin My sil was told she was having a very big baby every single time. Lots of panic and talk of induction/cs. Her biggest was 7lbs dead on.

With my own DC2, they were making noises about him being 9/10lbs. He was 6lbs 13oz.

And weight makes no difference in general terms to how easy the delivery is. It's position and head circumference which makes the difference. In fact, there's evidence to suggest that bigger babies are easier to deliver due to gravity. My 6lber and my 7lber both got ridiculously stuck and I had two emcs. This was all due to position.

PartyConfused Wed 02-Apr-14 20:44:06

Dd1 had 2 weekly scans in the last 10 weeks. She was predicted to be over a 1lb heavier than what she was at every bloody one of them. And...she was 6lbs 3!

So pretty rubbish.

isisisis Wed 02-Apr-14 20:49:45

Not accurate in the slightest. I had 2 scans, 2 days apart. First predicted a birth weight of 12lb 2oz, the second 8lb 4oz. She'd hardly lost 4lbs in 2 days! She was born 2weeks later at 9lb 14oz. I really don't understand why they don't give a range or even bother to comment at all when it's so inaccurate.

aclxxx Wed 02-Apr-14 20:53:53

Thank you Raxa and Partyconfused .
That is encouraging. I do hope so, it will be safe delivery

aclxxx Wed 02-Apr-14 20:57:03

Oh thank you isisis. What caused me to worry there were 3 professions in the room one was a fellow research Dr., the other were Sonographers. My mind went to overdrive and thinking I have eaten too much pudding and this is going to hurt

Clearlymisunderstood Wed 02-Apr-14 21:07:12

My sisters scan at 34 weeks said she was having a tiny baby, estimated weight at 3.5lbs and guessed at less than 6lb birthweight at term. My niece was born at 36 weeks weighing 6lb 7oz

isisisis Wed 02-Apr-14 21:09:56

My 1st scan was a sonographer & obstetric registrar, the second with the clinical lead professor for obs & gynae at a major teaching hospital (I had loads of complications). She was still wrong, but much more honest about the variability of measurements. It means nothing, I'd be more surprised if you'd posted to say they'd scanned you, you'd had the baby & they were right on the money.
Do you think your just having the almost term wobbles? I certainly did & know most of my friends did. I'd imagine it feels worse knowing you have a choice of delivery to make still as well. If only they had a crystal ball! Hope all goes well for you whatever you decide.

rempy Wed 02-Apr-14 21:11:33

Voodoo, it's mostly voodoo. And don't believe anyone who passes comment on your bump either. Including a midwife armed with a tapemeasure.

missmagnum Wed 02-Apr-14 21:15:57

I had 3 scans and lots of bump measuring post 30 weeks, was told to expect less than 6lb. Took tiny baby clothes to the hospital, he was 7lb 10oz! Dh had to hot foot it to sainsburys grin.

aclxxx Wed 02-Apr-14 21:20:56

As most mums here who will empathise with, there is nothing like pregnancy to make you a fanatic worrier. This baby is a very special surprise to us after 7 yrs of waiting or giving up! So every corner is wobbly moment. Rempy you made me chuckle with the comment of bump size.

So called work mates keep on commenting how big my bump is? numerous predictions of a possible big baby.

aclxxx Wed 02-Apr-14 21:22:51

congratulations missmagnum I will sleep easy tonight for sure

GoooRooo Wed 02-Apr-14 21:45:35

I was told "You're fat so you're bound to have a big baby". I had a growth scan at 34 weeks as they were so concerned and told I'd have a 9lb - 10lb baby.

He was 6lbs 8oz so bollocks to the lot of them I say.

Not accurate at all. Measured and scanned average size both times and had two big 'uns! wink

missmagnum Wed 02-Apr-14 22:23:22

Enjoy the next 9 weeks and try (although I know impossible) to not worry too much, hopefully our experiences have assured you they aren't always accurate.

Gingeroo Wed 02-Apr-14 22:29:27

Mine was way off the mark.

I had a growth scan at 34 weeks and I was told birth weight would be well into the 9lb range (can't remember exactly though).

As it turned out I went 2 weeks overdue and DS came out at a lovely round 8lb.

Not at all.

I was told to expect a whopper for my first. crapped myself till he came out, long and very slim (just like his dad) at 7lb 10.

You see these scans can't accurately estimate the muscle and fat around their bones, they just looked at the length of him and size of feet etc, and assumed he would be big. He is still so tall and slim that we had a letter from school telling us he was underweight when they started all that weighing and measuring of school children recently. (he is almost as tall as me and I can still pick him up and carry him up to bed if he is ill!)

I refused one for ds2 and he was 9lb.

Poppiesway Wed 02-Apr-14 22:48:22

As a sonographer speaking.: we cannot predict weights.. There's too many variable to be able to do that.. We can give an approx weight of that particular scan but not birth weight..

However.. When I had my last scan of ds2 at 36 weeks.. I was induced that day and he was spot on the 5lb 4oz weight the scan had said he was earlier in the day..

Weight is dependant in good measurements.. And the bigger baby.. The more difficult it is to get an accurate measurement of the head and abdomen

sdaisy26 Thu 03-Apr-14 08:11:54

Not accurate at all ime - ds was given a predicted birthweight of 9-10lbs at a 36 week growth scan. He was born on tues at 40+9 weighing 7lb 12.

frankiebuns Thu 03-Apr-14 11:18:45

My cousin had baby in december induced on her due date told 11lb baby he arrived 6hrs later at a tiny 7lb 2oz!

CarlyKins Thu 03-Apr-14 11:24:46

I can't answer this as I am due on Tuesday, but I have had lots of growth scans and been told my boy is bigger than average, weighing over 7lb at 36 week scan and estimated about 9lb. Am hoping he will be a bit smaller coz am worried but with all the responses on here it seems they aren't very accurate x

aclxxx Thu 03-Apr-14 17:21:27

carlykins best wishes! I will be watching to read your arrival!

Thanks everyone it is reassuring. Popsie I did ask how accurate on the margins of give and take, but they were confident on the weight. I do take on board sonographers do a great job. I certainly could not tell from the scan all the details they were looking.
Just wanted reassurance which I have received from all of you.

mowmylawn Thu 03-Apr-14 18:12:47

One of my friends was told during a growth scan very close to her due date that she'd have a low birth-weight baby and it came out 8lb 13oz. Consultant said 'that's not the same baby!'. So take that as you will ;)

weebigmamma Thu 03-Apr-14 18:18:02

Am finding this thread heartening! I was sent for the Gestational Diabetes test after they scanned and found my baby to be measuring 2 weeks ahead of dates. I am also overweight myself and I am wondering if that's partly what they're basing everything on, because my thin best friend has just had an 8lb 12oz baby and nobody passed a word on any of her scans. My section is next week and I will be intrigued to find out what size he really is!

Armi Thu 03-Apr-14 19:53:56

I went for several scans. Everyone very worried baby was too big ( I'm fat) then a few weeks later, great consternation she was too small. Much gnashing of teeth and terrible angst.

She was 7lbs 12 oz. Just about right, I reckon.

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