How accurate are MWs/OBs predicting size of baby?

[Loislane78]

21 weeks so only half way but have some complications. Got appt with consultant tomorrow so would like to start asking some qu's in preparation and you ladies always v knowledgeable :)

At 20 wk scan baby measuring average. I am 5'8 and DP a whopping but slim 6'7 so am half expecting long/big baby. If later on they can reasonably accurately predict baby size, this will inform my decision on birthing options (straight for CS). So interested to hear your stories on if they got it right.

TIA!

Well, Scan at 12 weeks was average, scan at 20 weeks was small, scan at 28 weeks still small, scan at 32 weeks still small. Scans predicted a 6lb baby, MW's going by my bump said a 9lb baby. DD was 5lb 13oz at 40+6. I am 5'4 DH is 5'11, both a fair bit overweight

Close friend's little girl was average on 12 & 20 weeks scan's, different set of MW's going by bump said really big baby, predicted another 9lb baby and she was 7lb 12oz at 42 weeks. Her DH is 6'8 and she is 5'6, her baby is long and has big feet. Both are fairly average.

SiL when pg with DNeice was average at 4 scan's, MW's kept referring her as bump measured up small, said small baby due. Was 9lb 6 1/2oz at 36+2. she is 5'3 and her DH is 5'10, very slim and dainty both of them. DNeice is now.

with three of mine they said htey were small, they were infact all 9lb+

with ds4 i again expected another large baby, my midwife thought he was big, but we were all suprised at him beign 10lb 13oz! water birth tho and all fine :)

with no 5, i KNEW baby was smaller, she felt smaller, but hospital insisted she would be big, they said 9lb + she was exactly 8lb at birth, so ime they arent that great at estimating size!

apparently they are generally about 10% out, so i would take it with a pinch of salt!

my bumps all measured small, but other than dd my babies were all big :)

I think with scans in late pregnancy they say + or - 10%, which is hugely inaccurate. Trying to predict a baby's size at 20 weeks sounds like total guesswork to me .

A long baby is not necessarily difficult to birth vaginally. Actually, a heavy baby isn't either. Can you say more about your concerns in this respect?

Hmmm, so doesn't seem v accurate!

I take Clexane injections and unless I'm induced early (so they know I haven't injected for x hours), I definitely wont be able to have an epidural and it's uncertain anyway due to restricted movement (dvt issues).

I know lots of women are fine with no epi, just feels like a safety net as will also be on ward and no birth pool available etc. Was just thinking if big baby would like some pain relief options beyond G&A and I understand induction sometimes causes additional interventions - ouch!

Thanks for your responses.

well i was induced with all 5 of mine as i always go overdue, but even with dd when i had the syntocin drip i managed fine with gas and air! god i LOVE that stuff and stay MOBILE, sit on birth ball, on all fours etc, is there no pool?

some hospitals will let you take in inflatable birth pools, obviously whilst on ward there wont be one but they do have baths? they should let you use that, or even stand in a shower and the hot water on your back/bump should help.

you can pethidine as well or whatever your hospital offers.

i think big babies deliver more easily tbg, ds4 was my biggest and easiest, whereas dd no 5 was the smallest and most painful i found!

look up alternatives to help with the pain, even if its just placebo like homeopathy etc, breathing, hypno birthing there are lots of things you can do to prepare yourself and the midwives will be there to help and offer support and alternatives if you cant have the epidural.

also if you cant have an epidural how will they do c section? spinal block or general? it may not be a better option.

i would be wanting a good chat with midwife so that you are clear on your options :)

good luck!

My midwife predicted the weight of both my DDs and she was correct both times. With DD1, she said 6 1/2 to 7lb - she was 6lb 12 oz. with DD2, she predicted 7 to 7 1/2lb and she was 7lb 4oz.

So pretty much spot on both times.

They told me dc2 wasn't big as I measured small for dates on the fundal height thing, she was 10lb 6oz, I was induced with 2 pessaries but other than that unassisted delivery and no stitches.

The scans aren't very accurate, neither is fundal height, neither is how big your bump is.

Hope it all goes well - it's not how tall they are (dc2 was 6 months old before she hit the length scale) but how big their heads/shoulders are that's the issue.

well ds4 had a MASSIVE head, it was off the chart at birth 42cm or something! and his birth was still fine and no i dont have a bucket fanny

i think babies position is more important that its size tbh so google optimal fetal positioning and get on all fours and make sure baby is in agood positions, dd my last and smallest, most painful labour was back to back!! little minx never turned and came out facing the wrong way up, it was still only 3 hrs and a few pushes, so very good for a back to back baby, but it was more painful!

Nobody ever said anything at scans but my community midwife who examined me a few weeks before birth predicted 'just shy of 7lbs' and sure enough that was exactly right - 6lb 15oz. With a lovely small head.

Ok so weight/length not a factor particularly, more head/shoulders and a good position, both baby and me during labour. I just need to ask lots of questions about different scenarios, like everyone needs to I guess.

I'd like to think I cope ok with pain and don't have my heart set on a particular birth, just want everyone safe with the reassurance of some back up pain relief options if necessary so I don't feel ELCS is best option (not keen).

Thanks ladies :)

I had a growth scan at 38 weeks because I was measuring big. They said he was average/normal, reckoned 7-8lb at term. He was 9lb8 at 39+4 and the little bugger turned back to back at the last minute. My community midwife was far closer

#1 was supposed to be massive - extra scans etc. born at 39 weeks 7lb 2oz.
#2 was supposed to be too small - extra scans etc. born at 39 weeks 7lb 4oz.

As an aside if you do feel an ELCS is best for you it is best to mention this early as it's not a quick process to get one 'approved' (this my have changed with the recent NICE guidelne changes though)

The only mw that told me DS was going to be 'cuddly' was the one that took my obs for 3 days before the birth! Every test and scan (fortnightly from 28w) i had said he'd be on the small side,They even tested me for GD as i'm overwight but hadn't gained anything by 30w, and he was 9lb 1. He was by far my easiest birth. (DD1 8lb 8, DD2 7lb 13)

We had a growth scan at about 36 weeks saying dd was going to be petite, all the midwives agreed. She then came out at 8lb 2oz. BUT I was induced so a) we were two weeks over and b) I'd been pumped full of liquid with the drip, so dd looked somewhat inflated.

At 6 months she's now a petite dinky dot just below the 25th centile, so overall, they got it fairly right.

For me MW said average size and she was right with all 5 as they were all between 7 and 8lb. My sister though was booked for a scan the day after dn was born because they were concerned about growth. Midwives said baby would be about five pound if she went to term. Dn was born the following day, in the ambulance on way to hospital (precipitous labour) weighing 9lb 12oz. I got to the hospital about an hour after birth and ds's tummy was as flat as a pancake midwives felt that her strong stomach muscles (she had barely had a bump) and baby's position had hidden the true size of baby.

Rubbish! My 20 week scan onwards I was measuring small. By about 36 weeks was measuring about 4 weeks behind so was sent for growth scan and they thought baby would be about 6lbs ish at 40 weeks. I did end up 15 days overdue but baby was near enough 9 lbs! So not accurate at all!

with my first, they claimed he would be about 8lb

He was 10lb4oz

There's quite a high margin of error ime

I can't actually remember what they predicted my second would be, but it was far less than the 10lb5oz he turned out to be!

My gynaecologist reackons it's not at all an exact science and doesn't put much value in the estimated weight, etc. He prefers to look at the mothers' weight gain, size of bumpr, previous history etc. They told me DS1 was "exactly average" at my 32 week scan. Turned out that when he was born by CS at 39 weeks (due to breech position), he weighed 10lb 3oz and his head size was off the charts....

DS2 (due on 20 May) is apparently a bit below average size according to my 32 week scan. Planning a Vbac, so I guess we'll see if it's true of not!

We had lots of growth scans with DS - the last one, on the morning I went into labour, put his weight at 8oz below his birth weight. As he was only 4lb 6oz, that's more than 10% out.

Problem is, with growth scans, they measure the babies proportions & feed them into some equation, so tiny errors in measuring the babies femur or head etc can cause big errors in the estimated size.

My friend had a growth scan at 38 weeks and was reassured she had a 7lb 7oz baby on board. Gave birth 10 days later to a 9lb 9oz whopper. That's also more than 10% out!

I was huge with dc1 and they guessed 8 lb. and said I was just moaning. He was 10 lb 8 oz.

DC2 they worried about another big baby, but dc2 was 8 lb.

Round here they seem to have no idea.

Good luck by the way!

I had to have additional growth scans because of my midwife claiming that my huge bump and huge husband meant a huge baby ... DD was a dainty 6lb at 41+3. Muppets!

I think it was down to the fact that I'm 4'11" and had too short a body and so no where to carry a baby other than sticking outwards.

Scan measurements were all over the shop and so pretty meaningless IMHO. In the words of Mr Gump. "Life's like a box of chocolates..."

All the best with the bump!