how spot on are ultra sounds??

Elouise - posted on 08/01/2010 ( 73 moms have responded )

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hi guys i was just wondering how spot on the weight of the baby is when they give you an altra sound? i was sent to get one done because i was measuring bigger for dates i am 34 weeks prego and he is measuring 2 weeks and four days bigger. They also told me he already weighs 6 lbs 6 onces.



thanks elouise :)

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Vicki - posted on 08/01/2010

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Notoriously inaccurate. I've heard so many stories of mums who were told 'your baby is too big, you need a c section' then had a baby of less than 7 pounds. I wouldn't believe it at all, it's usually just a trick to make you more compliant when they suggest surgery or induction. Your body is made to birth your baby, despite what the medical crowd say.

Kim - posted on 08/07/2010

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Mine was not good, they told me i was having a tall and heavy baby, he was 5 ponds 15 oz and tiny...

Marlene - posted on 08/05/2010

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I was told, at a 36w untrasound, that my daughter was 5lb5oz and *might* weigh 7lbs by birth. She was born at 39w5d and weighed 8lbs 11.4oz.... Not very accurate if you ask me!

Vicki - posted on 08/04/2010

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I like your sentiments Brooke. The amount of women who have been conned into surgery due to 'too small' or 'too big' baby is criminal.

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73 Comments

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Yalana - posted on 06/07/2011

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They are pretty accurate, from my experiences. With my first son, though, the doctor thought that u/s were overexaggerating and said my son would only be 8-8.5 pounds...he ended up being over 10! All my boys and my daughter (whom I am currently carrying) have measured at least 2 weeks ahead (my daughter is 3-4 weeks ahead...she's coming to dominate over her half-brothers and half-sisters! lol) She's going to be at least 9 lbs. at birth...if she's bigger than 10lbs 2oz, she'll not only break the record for both sides, but she'll beat her oldest brother! :)

Meghan - posted on 08/15/2010

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ive always heard the you should give a lb either direction when the give you the guesstimate.. They said my son would b 7 lbs 15 oz and he was 8 lbs 10 oz!

Mandy - posted on 08/15/2010

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not accurate, my fundal measurements said my 1st baby was big so i got sent for an ultrasound that said he was normal- he was 9.2lbs so he was pretty big, the old and true way of measuring seems to be good!

Alicia - posted on 08/14/2010

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Not at all accurate. My baby was had an ultrasound at 36weeks and she was 8lb 4oz, so it said. I had her 2days later via c-section and she was only 7lb 14oz. I had to go out and get some smaller clothes for her.

Tiffany - posted on 08/14/2010

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As others have said, I wouldn't worry to much about it. They may have estimated your due date incorrectly, as it's often just a guessing game. I went 41 weeks before my daughter came, and the ultrasound tech told me that the weight can be off by 1.5 pounds (either way). It's hard to get an accurate reading, as it depends on the amount of amniotic fluid surrounding your child, how hydrated you are, and various other reasons. Your baby will come when he/she is ready. Good luck and don't stress! Just read legit articles to educate yourself and enjoy the rest of your pregnancy.

Jennifer - posted on 08/14/2010

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The ultrasound was close to what our daughter weighed at birth, I had a midwife predict my baby to be a fair bit bigger than my first daughter and she was totally wrong!! our second daughter was 5 ounces and 5 cm smaller than our first. So please dont panic I hope this helps :-)

Binaz - posted on 08/14/2010

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they r nt tht spot on i had an utrasound the day i was admitted 4 delivery i was told my baby wieghs 2kgs 400gms & bezad was the same day weighing 2kgs 700gms

Bernadette - posted on 08/13/2010

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they are really only an estimate. They measure the head size, length of body and limbs, etc, and make an estimate from that. My daughter was predicted to be between 7.5 - 8 pounds, but was only 7lb 3oz. My sister had a baby and they predicted he was going to be "big" - I think they were thinking around high 9s - 10. He ended up being 11lb 3.5 oz. They can't really tell for sure, other than an estimate.

Tara - posted on 08/13/2010

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inaccurate! they told me i may need a c-section bc they had her weighing in at over 9lbs ( i have a little frame) she ended up being born naturally weighing in at 7 lbs

[deleted account]

there are a lot of factors that go into the "estimate" of an ultrasound. If you want to have a natural birth make sure your doctor is one you trust will do what you want and only call for a csection when it is absolutely necessary. My Eleanor was measured at 6 pounds a week before she was born and she ended up weighing 8 lbs 12 oz at birth. Most moms do not have ultrasounds that close to having a baby unless they are checking other factors so most people haven't a clue what their kid will weigh. Lots of people have big babies, lots of people have csections, lost of people have big babies and a natural birth. I wouldn't worry too much unless your doctor is indicating that you might need a c section. Then just make sure the doctor is willing to see your plan through at least as long as it is safe.

Heather - posted on 08/13/2010

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I wouldnt put too much faith in then i was told i was having quite a small baby and he was 9 pounds 4.5 ounces! and i was refused c sec because they refused to accept that i was having a big baby regardless of what i said. dont worry too much about the docs!

Laura - posted on 08/13/2010

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My baby was bigger than they told me. The ultrasound technicians guessed 6Ibs and my daughter ended up being 7Ibs 5oz a couple days over due.

Dawnyka - posted on 08/13/2010

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Ultrasounds are very inaccurate.

My due date was May 31st, 2010 with my 3rd child. I still hadn't gone into labor by June 7th, so they gave me an ultrasound and decided to induce me the next day. They said the baby was 8.5 lbs. Well, after 26 hours of a very complicated labor, my son was born 10 lbs, 6 oz. - almost 2 lbs lighter than the ultrasound said. And they also said that he looked like he was more like 38 weeks, instead of 41 weeks. I can only imagine how big he would have been if they'd let me carry him another couple of weeks.

Lauren - posted on 08/13/2010

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Not very. My LGA ultrasound predicted an 8lb baby and Ben was 10lbs 3oz & I ended up with a c section after patosin didn't work

Anne - posted on 08/12/2010

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ultradound for size is notoriously inaccurate, especially the later you get in your pregnancy. Even if they happened to get his size right, 6lb 6oz at 34 weeks isn't big with the time you have left. Your body will not grow a baby you can't birth. I birthed a 10 pound behemoth at home with my midwives with barely a first degree tear where even 1 stitch was debatable. Just say no to ultrasound unless you have unexplained bleeding or some other medical reason to have an ultrasound. checking for size is not a valid medical reason.

Kristen - posted on 08/12/2010

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Dont trust them!! I got told at 36 weeks that my daughter was already 8 pound so i was not allowed to attempt a natural delivery. When I had the ceaser at 38 weeks, she weighed only 7.1 pound. (you can imagine how angry I was at having been made to have unnecessary surgery and missing out on experiencing labour) Speaking with the midwives and doctors afterward, they all said that ultrasounds later in the pregnancy are not at all reliable.

Angela - posted on 08/12/2010

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For my son, he was averaged at 8 lbs, 14 oz at week 40, I was induced at 41 weeks and he was just over 9lbs at birth. For this baby, my 2nd, I am 37 weeks, 5 days and they averaged him/her at 7lbs, 14oz but the doctor said it's give or take 14oz. With my son they said give or take 30%. So I think there is validity to it, but it's just a machine and not dead on 100% of the time. I think it depends on how good the tech takes measurements.

Madeleine - posted on 08/12/2010

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I was always under the impression that the size of the baby was estimated according to a measurement of the baby's head, and that it was just that - an estimate.

Our big ultrasound snafu was with the sex of our baby. I have a wonderful ultrasound snap shot in my son's baby book that reads "It's a Girl" and points out a classic shot of in-the-womb little girl parts. (Three White Lines.) Either he was tucking it back or mooning us. Surprise!

Cori - posted on 08/12/2010

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I had polyhydramnios, and it completely skewed the ultrasounds to show him as much bigger than he really was (to my relief!).

Melissa - posted on 08/12/2010

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dont worry! i knew someone who was measuring over 8 lbs and the baby was less than 7....they can be off either way by a pound or 2. I was told my baby would be 8 1/2 pouonds and he was less than 8.

Robin - posted on 08/12/2010

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They estimated my babies weight at 8 lbs 6 oz. I nearly fell off the bed because they said he was so big, and when I delivered he was 8 lbs 5 oz.

Rosa - posted on 08/12/2010

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I was told that based on my ultrasounds if my baby kept growing like she had been that she would be 3.3kg at birth. She weighed 4.2kg at birth, so i think it is all just a guesstimate.

Jessica - posted on 08/11/2010

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i hope i'm not repeating what everyone else has told ya but w/ not having time to read all the other responses i'll just share my story. i was measuring farther along and my OB wanted to switch my EDD but with the guidance of a doula and my Bradley Instructor was is also an RN of 20 years, they both pointed out that it's against the AMA to change an EDD after the 8th week. Reason being is up until the 8th week we are all groing and spliting cells at the same rate. After 8 weeks thats when genetics plays a huge factor. Imagine the concept that Shaq and yourself were the same size at one point :) So basically IF anyone is encouraging you to change EDD's, don't. Also the further along in your pregnancy the more off the ultrasound will be. It happened to a friend of mine and they advised her to have a c-section b/c the "baby was going to be to big" and they were saying the baby was going to be 8.5-9 lbs and when she was born she was smidge over 7 lbs. Same for me too. They told me my son was measuring 8 lbs at 34 weeks and that he was going to come early. When he was born at 41.4 wks he was only 7.15 lbs... not even 8 lbs. If you get an honest ultrasound tech, they will tell you that their measurements can be (and usually are) off by as much as 2 lbs!!

hang in there and if you have any questions to what i shared just drop me a note:

-jess

Andrea - posted on 08/11/2010

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ours was right on. we had many all along,one the week before and the day of and they were all within 2 ozs.

Jennell - posted on 08/11/2010

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Hi Elouise,

I love your name...it was my great-grandmother's name! Anyway the day I had my baby they did an ultrasound and estimated her at 7lbs 4ozs and she was delivered 6lbs and 5oz. So, I would say they can be off by quite a bit. Best of luck to you in the rest of your pregnancy!

Bianca - posted on 08/11/2010

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i asked my sonographer how big they thought my son would be at birth and they said around 8p and when he was born he was 8p 7o so they were quite close and my doc said that my belly was measuring bigger then it should be whilst i was pregnant n that id have a big baby.. but he wasnt as big as they thought hed be.. its possible u could jsut have alot of amniotic fluid which is making ur belly bigger or u cud just be having a big baby.. dont stress too much :)

Jessie-Ann - posted on 08/10/2010

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My OB, even with more than 20 years experience, told me that my daughter would be about 7 and a half lbs. When she was born, she weighed 9 lb 3 1/2 ozs. You just won't know till bubba arrives :)

Erin - posted on 08/09/2010

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VERY INACCURATE!!! I was told my son was approx 7 lbs by the ultra sound tec....then she told me it could be off by a lb either way......so she should have just said she didnt know!...lol my son was born 5lbs 9 oz!!

Stephanie - posted on 08/09/2010

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They were fairly accurate for my pregnancy, although I got a few comments about a large baby I had a 7lb 11 oz baby with no trouble, no medication (not a lot of time and am more fearful of needles in my spine than pain), in a labor that while extremely tiring and painful (full on contractions the entire time until pushing lasting at least a minute long) it lasted just 4 hours. Yikes! I did have a friend who got a c-section one month before the due date because they warned the baby was really large (she was small) and she was sure of her conception date and she had the baby a month early at 8.8lbs - so in her case, it was probably a good thing but the baby had to be in the NICU until his due date, and I think she regretted not waiting another week or so for the c-section (what would have been the harm?). (Doctors really don't aways know best, is my feeling). So people experience the gamut. I think you really have to trust your instincts, stick up for what feels right to you, and keep the baby inside as long as it's possible up to the due date.

Amanda - posted on 08/08/2010

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I wouldn't believe them. My OB when I was pregnant with my son estimated just by palpating my stomach. She had 30 years experience and was REALLY good, had a great experience and trusted her (and was spot on @ just under 7 lbs). Forward 5 yrs, I had an ultrasound at 36 weeks and was told she looked to weigh about 8 1/2 lbs even with possible pre-eclampsia and history of small babies in the family. 3 days later she was born at just over 5 1/2 lbs. Inexperienced tech or small uterus...who knows but WAY off no matter how you look at it.

Whitney - posted on 08/07/2010

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not very good. my daughter i just had in july they were estimating almost 9lbs and she came out 7lb 12oz doctors were very surprised but i was sooo happy

Melissa - posted on 08/07/2010

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I was always measuring 2 weeks bigger than the current week. The doctor told me my baby would probably be around 8 lbs. I was induced at 39 weeks for preeclampsia and she was 10 lbs 5 oz.

[deleted account]

Sorry, I haven't had a chance to read the other posts, but we were told that our bub was a big boy, when he was born (induced) he was only 7pound 2 ounces. The only thing that was spot on was the 3D pic, we have a photo of him making exactly the same face at 5 months, they're identical. :-)

Karren - posted on 08/06/2010

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Mine were pretty good, they told me I would have big babies and all three of mine were over 10 pounds. They did talk of a c section but I said no. I had all 3 of mine naturally with no drugs.

Bridgette - posted on 08/06/2010

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They can be off easily by a pound. You can be measuring bigger than dates for different reasons like the position of the baby. I wouldn't worry too much.

Doreen - posted on 08/05/2010

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My ultrasounds were pretty accurate ... at my last ultrasound they estimated 8lb 7oz with head circumfrence at 14.75", and she was born 5 days later (c-section due to breach position) at 8lb 14oz and 15". Her weight went up consistently went with each weekly ultrasound.

[deleted account]

I was told my daughter was going to be 6 lbs. 4 oz. exactly 2 weeks before she was born. She was born 5 lbs. 15 oz.

Stephanie - posted on 08/05/2010

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They told me I was measuring 2 weeks big and when I went for the u/s they estimated 7 to 8 pounds...she was 6 pounds 10 ounces. It didn't matter, I was not going to let them give me a c-section! I was gonna push regardless...

Kathy - posted on 08/05/2010

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I guess it all depends on who's doing the ultrasound and the equipment because weight wise mine was very accurate. 2 weeks before my due date the estimated weight was 6lbs 3 oz, with the 1/2lbs/week gain that would put her at 7lbs 3oz on the due date. She was born the day before the due date at 7lbs 4oz.... thats very very close...

Cara - posted on 08/04/2010

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I just had my 12 weeks ultrasound on monday. The tech that did it told me that usually the later the ultrasound is the more inaccurate it is(except for determining baby's gender). When I was pregnant with my daughter I was told she would be an avg sized baby of about 6-7 lbs. they really didn't think she'd be more than 6.5lbs which i found funny since at my 20 u/s she was already heavier than most at that stage, but again those aren't always accurate. Anyways, when my daughter was born she weighed in at 8lbs 7oz. That being said....when my SIL was preggo with my nephew they told her that he was going to be a very big baby, around 9 lbs. When he was born he only weighed in at 6lbs and a couple oz.

Claire - posted on 08/04/2010

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When i was 36 weeks with my daughter i had an ultrasound sound and they told me i would have a 6 lbs baby, well they were way off she was born 8.13 lbs, and was far from small lol, so now i never believe what the docs tell me, i just wait and see :)

Shelby - posted on 08/04/2010

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With my daughter it was pretty spot on at 36 weeks my daughter was 6 pounds 4 ounces and 3.5 weeks later when I had my daughter she was 7 pounds 11 ounces. I was told though that it can be up to 2 pounds difference(either weighing more or less than what the ultrasound says)

Katie - posted on 08/04/2010

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I got an ultrasound when I was 41 weeks, and they told me that my little girl was going to be 8lb 5 oz. When she was born she was 7lb 8 oz. I've heard that they tend to be off about a pound.

Brianna - posted on 08/04/2010

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ultrasounds are not all that accurate. My placenta was half the size of a regular one and i have 3 ultrasounds and they never caught it! No wonder i was so small im lucky my daughter was 6lbs 6oz.

Jessica - posted on 08/04/2010

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I was gestational diabetic when I was pregnant and at around that time they gave me an ultrasound and told me if they grow the 1/2 lb per week like projected then my daughter who weighed 7lbs 2 oz at delivery would have weighed over 8 1/2 lbs. I don't trust them. the measurements are going by average. Also I knew my conception date and they kept telling me I was one - two weeks less along than what I was

Megan - posted on 08/04/2010

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The ultrasounds are pretty accurate give or take a pound. I had an ultrasound done the same day I got induced. They estimated him to be 7 pounds 12 ounces and when he was born he weighed 7 pounds 3 ounces. Pretty close.

Brittany - posted on 08/04/2010

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Ultrasounds really aren't very accurate...the only thing they got right with mine was my son's gender and the fact that he has a large head. Before my son was born there was a shadow that showed up on every ultrasound in his brain and even the ultrasound they did after he was born...it turned out to be nothing, just a shadow, but they had to do an MRI to find out for sure because ultrasounds aren't very clear. Because of how big my son's head was they also told me he was going to be like 8 pounds and ended up only being 6 1/2. (They told me 8 lbs. when I was 32 weeks and his head measured at 35 weeks and I went full term, so I thought he was going to be quite a bit bigger then he ended up being.)

Crystal - posted on 08/04/2010

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I have three children and not one time was it accurate. My first they said she was doing fine, gaining weight healthy in size. She was full term,actually like a week overdue and she weighed 5.8. My last one they scared me to death cause they said I was going to have a 9-10 pound kid. She ended up being seven pounds even. So it's not always right. You hear more of them wrong then right.

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