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How accurate are these ultrasound weight predictions? That's baby's weight, not mine!

(20 Posts)
Belgrano Thu 16-Jul-09 14:50:08

I've had a few as they were worried baby wasn't growing enough and they seem to say it's a whopper - about 9 7 oz lbs at 40 weeks if it carries on on this curve. DD was 7 lbs 15 oz.
I am 39+5 now. Anyone else had experience of late scans and can tell me how reliable they are at predicting the actual weight at birth?

Belgrano Thu 16-Jul-09 14:50:55

PS it's the ones where they measure abdominal and head circumference and femur length and then do some clever sums...

greenbeanie Thu 16-Jul-09 14:53:01

I was told that if they are predicting a big baby it can be out by 20% either way. I had scans as both of mine measured big, I was told my 1st would be 10lbs at term - actual weight 9lb15 at 39 weeks when born, and second ds would be 8lb7, he was 10lb7 when he arrived spot on his due date.

I would take it all as a rough estimate rather than actual fact. smile

sleeplessinstretford Thu 16-Jul-09 20:31:12

first one 'very small but my fault because i smoked' (yeah yeah) it was 9lb12 but posterior so fitted into ordinary size 12 clothes at 42weeks.
2nd one,had a scan at 36weeks told it was 7lb8 then-i have 42week pregnancies-they measured head/bones/babies belly too i think-
anyway-6 weeks later i popped her out 9lb8 rather than the forecasted potential 11lb5 as mooted 8 weeks previous *whereby i nearly shit my pants and demanded a cs*
i think it's a bit of bollocks myself and why worry you-what you going to do?start smoking to make it smaller ffs?!?

Beccabump Thu 16-Jul-09 21:14:54

Hey Belgrano

As you know my scans were very inaccurate!

I measured all over the place - ranging from normal to 'my god it's huge' and out he came at 38+1 and 7lb5oz!

Try not to worry, it's incredibly rare a woman's body will grow a baby bigger than she can manage.


WhatFreshHellIsThis Thu 16-Jul-09 21:16:15

They got DS2 wrong by over a pound.... smile

lisad123 Thu 16-Jul-09 21:16:42

I was told, normal weight, both my irls were term and were 5lb and 5lb 3oz, so i never quite believe them hmm

Mintyy Thu 16-Jul-09 21:18:43

At 39+2 I was told 8lb.

DD born at 40+2 9lb 2oz

AnybodyHomeMcFly Thu 16-Jul-09 21:20:43

Not very accurate. I was told DD was 7lb and she was only 6 at birth

AnybodyHomeMcFly Thu 16-Jul-09 21:22:13

Oh and they thought she wasn't growing properly too as I had a very small bump. But it turned out she was just a small baby and I was "all baby". She was and remains absolutely fine.

loisstella Thu 16-Jul-09 21:34:12

Don't worry - I was told at 38 weeks baby was 8.10 and that she would be 10 pounds if I went over term. Mia was born at 41+5 weighing a beautiful 7.7
I don't really believe in these predictions much anymore!

Belgrano Fri 17-Jul-09 13:34:16

Ooh thanks everyone, I feel much better!

itsalwaysthequietones Fri 17-Jul-09 15:28:03

agree with general sentiment - had small bump w/ DD 3 extra scans because of concerns she wasn't growing properly. Estimate was 6lbs - she was actually just under 8lbs.

NorkilyChallenged Fri 17-Jul-09 15:30:47

I don't know anyone who had one of these be accurate actually.

Most recently my sister was told she was having a big baby (nearly 10lb extrapolating from weight they "guesstimated" on the scan at 35 weeks) and her dd2 was 7lb14 (smaller than her dd1).

She had been panicking and nearly asked for elective cs...

ready2pop Fri 17-Jul-09 20:11:12

I had a scan the day before DS was born and they predicted his weight at that point at 9 lbs. He arrived the next day and was 5lbs 13oz. When I asked the dr about it she said that the weight estimates were pretty much a waste of time. If you think about it they are using a computer mouse to click on a fuzzy, squiggling image on a dodgy black and white screen - how accurate can they really be?

Claire2009 Fri 17-Jul-09 20:20:29

Told at 32wks on both, if I carry to full term Dd/Ds will be 3-3.5kg

Dd born at 41+ 4 - 3.750kg - 8lbs 4oz
Ds born at 41+6 - 4.150kg - 9lbs 4oz

cory Sat 18-Jul-09 09:37:18

Mine were both out by a bit, but still worth having as they did show quite correctly that both my babies were small and growing too slowly.

itwasntme Sat 18-Jul-09 09:44:21

I was told at 36 weeks that ds was tiny for his dates.

He was born 3 weeks later at a respectable 7lb.3oz.

shelleylou Sat 18-Jul-09 09:59:21

I had a scan at 37 weeks and was todl ds would be 5lb11oz or 5lb12oz. He was born at 40+3 and needless to say i didnt believe MW when she first told me he weighed 8lb50z

LittleMonkeysMummy Sun 19-Jul-09 07:54:45

I was told DD was large for her age (at 38wks she was predicted to be at least 10lb) Born at 40+4 weighing a whopping 6lb 11oz hmm Turns out she was just a long skinny freak with a large head grin

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