Estimated birth weight versus actual one


I've been recently hearing loads of stories of people who were given an estimate of how big their babies would be and then the actual birthweight being completely different.
for me I was told at 40 weeks that my baby would be 8 1/2 lbs - 9 lbs but no bigger than that. He was 10 lbs 10ozs. Aother friend of mine was told (by scan) that her baby was 7lbs at 35 weeks. She was brought in early 3 weeks later and had a 6 and a half lb girl.
Anyway, I was wondering if birthweight estimates are ever completely accurate and if they're often wrong then what's the point of them?
hi lynn,
i'd love to know meself.
in both my prgnancies i was sent for diabetes testing (not particularly pleasant), because i was having 'big babies' (both times negative). granted the first fella was 8lb 13oz, big enough but i was told that my second was a fair bit bigger, so i was at my wits end thinking how i was going to push this one out. when i arrived at the hosp and was examined and told i couldn't have the epidural as i was nearly ready to deliver, i was frantic . ten minutes later number 2 was born weighing in at a not so hefty 8lb 3 oz. delighted though i was that it was over and all was well and delighted how much better i felt after, not having had the epidural. i was just a little bit cross that was led to believe i was having a moster and this had played so much on my mind.
so i think the next time i'll tell them not to bother telling me 'cause in my experience they're are just taking an educated or at times not so educated guess!!!!!!!
I had a scan at 29wks because DS was big for dates, can't remember what they said exactly, but after taking that weight and adding on the usual 0.5lb weight gain per week, they were spot on. DH asked me what my guess for the weight was when I was in labour at 39wks and I said 8 pounds. He was exactly that!
My scans were out re weights. Scan week before boys were born showed biggest twin (Twin 2) to be about 5lb odd or so (can't remember exact ounces) and twin 1 to be lighter. When Twin 1 was born and weighed he was 6lb 12oz so I thought they'd got them mixed up and it was actually Twin 2 that had come first and Twin 1 still to come. Turned out Twin 2 was 8lb 8oz so they were a mile off there.
on my first at the 34 week scan the obs. said it was going to be a big baby (a 10lber) but she was born at 39 weeks and weighed a nice 7lbs11oz and on my second she thought he would be small as he showed a growth problem at 34 weeks, he was born at 38weeks weighing a nice 7lbs10oz so definitely in my case they were weigh off.
Gosh Holly you must have been in agony carrying the twins around, they were big guys for twins!
DS ws estimated to be 8½lbs, was 2 days overdue and was 8lbs 10ozs so I reckon the weight estimation was fairly accurate!

Don't know about agony but I couldn't walk at the end
My obgyn gave me a totally inaccurate weight - but my GP who only saw me once at 31 weeks said dd would be 7lbs 5 ozs and she was 7lbs 4.5 ozs - pretty much spot on I would say!!
On DD1 when I was 39wks pg the midwife wanted me to go for a scan because she was concerned that the baby seemed very small. I asked if I could wait until the following week for the scan (wanted to keep them to a minimum) and the day before I was due back I delivered an 8lb11oz baby
On my second pregnancy everyone that I saw in relation to the pregnancy kept telling me that I was going to have a small baby...the doctor that did aech of my scans said that the weight estimates given during pregnancy are + or - 500g (weight at time of scan). He never actually gave a weight for the birth. But apparently when the midwife would measure the height of my bump it wasn't very big given the stage of the pregnancy. When I went it to be induced (2weeks over) the midwife said again "oh do you know you are going to have a small baby, your bump is only the size of a 7-8 month pregnancy"!
Tom was born and weighed 3kg410 and measured 52cm - a totally average sized baby and not at all what I would consider small!!!!
They said Oisin was about 9lbs. He was 8lbs 6oz when he was born at 38.5 weeks.
They told me at a scan at 31.5 weeks that this baby is already about 5lbs in weight - so to expect a 10lb. Also sent for GTT which was negative. IN fairness babys tummy is huge on scan and his legs are so long. I am having a 3d scan next week so wonder whether that will have the same outcome.
I've wondered for some time about how useful scan estimates are. Didn't get any strong predictions for No.1 except that he was about normal, and he was 7lb 10oz. With No.2, they said he would be 'on the big side'. Funnily enough, at around 23 weeks I was chatting to the consultant about baby size. She asked me how much my first baby weighed, then she glanced at the (mini) scan and said, "I'd say this one will be a bit bigger, around 8lb 3oz." Anyway, I was sent for a big scan a few days before he was born as they concerned he was big and they said "between 8 and 9lb" (how useful is that??!!).
At the end of it all, he was 8lb 3oz, so a consultant speculating off the top of her head at 23 weeks was accurate and a sonographer doing detailed measurements three days before the baby was born could still only give a very broad spectrum. How useful is the whole thing, really?
Something I reckon you should if your consultant says your baby is going to be big, is you should say "what actually is your definition of a big baby?" Because not everyone has the same idea. In my mind, a big baby is over 9lb, but for some consultants a big baby is on the upper end of the 7lb range. So it's worth clarifying.
My first was "measured" regularly, because she was considered to be "on the small side of normal". On Holy Thursday I was told she was now 7 lb. She was born on Easter Sunday and was 6 lb 9 oz, so almost 1/2 lb out. Because she was small, this one is also being monitored for size. Last Monday, at 33+6, I was told (s)he was 5 lb 5 oz, so heading for at least average size. (S)he certainly feels bigger. The consultant doing the scan was thrilled - I'm not too concerned myself, so long as (s)he isn't too big to come out!
A friend of my sisters was told at 34 weeks that her baby was 8lbs and would probably grow to about 14lbs by 40 weeks so she really should have a section BUT it was her CHOICE! How on earth is it her "choice" after being told something like that.Well they sectioned her at 37 and a half weeks and her baby was .................7 AND A HALF POUNDS!!!! She really wanted a vb and so she felt she was robbed of her birth experience.That'll just tell ya how sooooooo wrong they can get it.
I was told by my doc that i wouldnt have a "big baby".She said he was a healthy size but would most likely only be about 6-7 lbs.While she was on holidays her stand in told me that my baby was not small at all.Now who do ya believe.Anyway,,,turns out her stand in was right,,,he was 8lb 12oz! But to be honest,,NO ONE thought he'd be that big as i was very neat.But he was in a head down position from even before i was 24 weeks so maybe he was just all tucked up neatly inside me !!??!!
Im surprised at how many women ive come across that dont know that its just an ESTIMATED WEIGHT and there is no way of telling the babies EXACT WEIGHT till of course it is born.
On My first baby Iwas told he was about 61/2 7 lbs, He weighrd in at 8lbs 3 and a half ounces, I was also told that his head was very well down and " two pushes and baby will be out" Took me 3 hrs pushing and a ventouse To get him out.
2nd baby was told she would be bigger than first, aroung 8 and a half lbs, she was exactly 8 lbs though, Even though I looked massive which was due to me carrying 2 bags of water !!! At the end of the day its just a guess, and should be taken with a pinch of salt!!!
I wouldn't trust a u/s estimate with a bargepole myself.
My sister was told at 32w5d that her baby was "already over 2600g" and she should expect a 4000g+ baby at 40 weeks. He was born yesterday, at 37w2d (spontaneously, not induced) and weighed all of 2540g, totally normal for that length of gestation.
The estimates are done by comparing the measurements of various parts of the baby's body with the average for that gestation, estimating a due date for each measurement, averaging them out and then comparing with how far pregnant you actually are.
According to my notes, from a u/s done at 28 weeks exactly by my dates, this baby's head is due 2 weeks before it's abdomen (!) so the average is my actual due date and the estimated weight given was that of the average baby at 28 weeks gestation. Given that DD was over 9 pounds/4kg at birth, that made all the medical people happy . Personally, I'll believe it when baby appears and is actually stuck on a scale.
i was scanned at about 35 weeks as i was huge (had already had negative diabetes tests), i was told the baby was about 9 1/2 lbs already, but that this could be wron by 10%either way.
i was told to return at 39 weeks for a repaet scan, to see what i had in store for me. at this scan they were very reluctant to tell me the weight, saying they can be innacurate. so, to compensate, i asked them to tell me the sex!!! (they got that right!)
two days later i delivered an 11lb 9oz whopper!!
im wondering if the real reason they didnt tell me the weight was because they thought i'd have a nervous breakdown!!!
I was told by gynae that DS should be 8.5 - 8.75 lbs - he was 8lb 10oz so pretty spot on!
No size estimates yet on #2.....
well, from reading all of them the estimates seem to be fairly random, like people estimating the sex of your baby. It doesn't seem to be a very exact science.
The day before I gave birth on my last baby I was told "about 9lbs", a few weeks before that "not too big but not too small" - he was 11lbs 1 oz!!
It was only from a feel of my tummy but still!
I was told between 7 and 8 oz and she was 8oz 4lbs so not too far wrong!
In my case it was spot on - I was told between 8 and 8.8, he was a week over and he was 8.15.
My gp told me he was small for dates and that he would only be about 4.5 - 5 oz. He must have been hiding or something as he was 7.2
I was told I was having a small baby............he was 9lb 9oz..I don't know what they call big!

For More:

Coats on in the car??
My big boy is starting playschool tomorrow!
FAO Marie Aine
Sick Toddler - I feel terrible!!
finger food for a teething 15mth old?
What is best Footmuff/Snuggler for McClaren Quest?
How much does your toddler weigh?
Perfect Sleep solution for Toddlers