Growth Ultrasounds....how accurate?

KristiKubic · April 2014

I am 35 weeks tomorrow and they have guessed I have a big boy most of my pregnancy due to my husbands size. I measure right on track and have only gained 25 lbs up to this point. My doctor is not overly concerned and feels he will just be a bigger baby however every time I get an ultrasound, they are the ones who seem to be concerned that he is so big. So they did a growth ultrasound yesterday and they are estimating him to be 6lbs 12oz at almost 35 weeks and that his head is measuring at 37 weeks. I am not surprised and I have planned for a 9lbs baby the entire pregnancy again my husband is a big boy, 6"2, 250, broad shoulders, played semi-pro football.....big boy. They say these ultrasounds can be a +/- 1 pound but either way that would put him between 6lbs-7lbs.

Has anyone else had this done and if so what are you doctors saying? Just curious how much stock I should put in this or not. Right now I am not concerned or worried about him being big since I have planned for this. Just wondering if others have gone trhough this.

ElTrain5 · April 2014

"Significant error was seen while estimating fetal weight by ultrasound. Depending only on the fetal ultrasound for the estimation of fetal weight can lead to unnecessary obstetrical intervention."
https://www.ncbi.nlm.nih.gov/m/pubmed/23132481/

dmahanWed170597 · April 2014

I am not a very big person (5'4" only gained about 5 pounds) but my husband is large. My DS was only 7 pounds and a week early. Since about 25 weeks this baby has been measuring 2 weeks ahead but my MFM has not been concerned at all. Even when his head was in the 70%. I was freaking out but he said it was nothing to be concerned about.

flojo973 · April 2014

I wouldn't put too much stock in their estimates. They told me the way that they estimate is a formula based on head size, tummy size and femur size. To me that doesn't correspond to weight at all. And in your case it sounds like it might be skewed because of the larger head measurement. I would take it with a grain of salt.

flojo973 · April 2014

@lyracelesti - my baby was measuring the opposite - small head, bigger stomach, biggest femur. I'm going to give birth to a super tall pea-head! We should combine our babies and average them out.

curlylocks3 · April 2014

They aren't the most accurate things in the world. In a poll on a different board moms seemed to be split about 50-50 on the accuracy of their last growth scan and actual birth weight (half being right on target and half being wildly off).
With that being said, I think they are more helpful when being done at regular intervals and you can see if progress is regular, or dropping off. I believe they can be beneficial for some situations but I wouldn't be too concerned about baby measuring big on one scan.
With that being said

snowpants · April 2014

As others have said, they're not all that accurate so don't worry too much about it. Of course, they can be off in either direction... my first pregnancy the ultrasounds were all measuring baby to be big and my doctor thought baby could be 8 pounds. Baby was 9 pounds, 10 ounces. (So I always laugh when people argue that the ultrasound might be off by a pound or two, cause yup! Mine sure was.)

But hey, I birthed her just fine and she's awesome.

efino87 · April 2014

KristiKubic I wouldn't put too much money on it. I also just had a growth scan that reveled at large baby measuring 3-4 weeks ahead. Since my DH, his brothers, father and recently our nephew were all over 10 lbs at birth, I have always been aware of this possibility BUT every woman''s body is different. My SIL was able to push out the 10lb nephew without trouble and a friend recently delivered an almost 11lb boy all natural. Some women struggle to deliver 6-7lb babies because of their positioning/bone structure/ect.

Keep an open mind about interventions and take some time to research labor positions that would make birthing a bigger baby easier. When all is said and done you could still end up with a 7lb baby.

JNerd · April 2014

At 30 weeks they told me ds was already 6lbs. I was terrified of a huge baby given how much weight a baby gains in the last 10weeks (1lb/wk).

They were totally wrong as ds was born 6lbs 13oz (exactly on time too).

Take it all with a grain of salt.

MissBHaven1024 · April 2014

You are right that ultrasounds can really go up to a pound difference in either direction. At my ultrasound last week (32w1d), Isaiah arms and legs were measuring 34 weeks and his head was measuring 36 weeks. His weight estimate was 5lbs, 5oz (about 3/4 weeks ahead).

From my personal experience, my ultrasound estimations have been pretty accurate with my kids. I've always felt that Isaiah was a bigger baby, so to hear those numbers didn't surprise me at all.

Just based on your husband's stature, I would prepare for a good size baby (7.5-8.5lbs).

kks4471 · April 2014

I'm a sonographer, and completely agree that they're not that accurate. I was talking with the MFM I work with and see for my scans, and she said the biggest problem is that we measure the femur thigh bone, and not the cute chubby fat surrounding the thigh. Abdominal measurements are a little more accurate because they include the belly fat. Just a little insight for you all!

RaeJ004 · April 2014

I'm more worried that they're guessing your baby's large size based on your husband's current size. My DH is 6'5", 260 and was 9lbs at birth. My brother is 6", 190lbs and was 12lbs8oz at birth. His current size has nothing to do with the size of your baby. I would look more at your sister's children's size at birth (if you have any), and after that look at your mother's children's sizes at birth.

I'm 5'2" and gave birth an 8lb15oz baby easily. My sister's are both of comparable size and gave birth to 10lb+ babies easily. And like I said my mom gave birth naturally to a 12lb8oz baby. Don't let it stress you out.

bumpuser9343355 · April 2014

At my last appointment, my doctor told me Baby's head was measuring "larger than average". That totally freaked me out, but my mom reminded me that that could be as little as a millimeter of difference and to calm the F down. That put things in perspective a little

)

nikki0808 · April 2014

My OB told me that the growth ultrasounds are mostly inaccurate at this point. She said the most reliable measurement as far as size after 20 weeks is femur length.

ETA: My biological dad is 6'7" and my mom is 5'6" -- my brother (same dad) was just over 7lbs and almost a month overdue. I was 6lbs9oz on time. My other siblings' dad is 6'5" (very similar build) and they ranged from 7lbs (sister #2 and brother - mom had GD with him) to my 1st sister who weighed 10lbs 2oz (no GD with her)... I'm thinking it just depends on baby and the pregnancy. Just because you have a big build dad or mom doesn't = big baby.

nikki0808 · April 2014

RaeJ004 said:
I'm more worried that they're guessing your baby's large size based on your husband's current size. My DH is 6'5", 260 and was 9lbs at birth. My brother is 6", 190lbs and was 12lbs8oz at birth. His current size has nothing to do with the size of your baby. I would look more at your sister's children's size at birth (if you have any), and after that look at your mother's children's sizes at birth.
I'm 5'2" and gave birth an 8lb15oz baby easily. My sister's are both of comparable size and gave birth to 10lb+ babies easily. And like I said my mom gave birth naturally to a 12lb8oz baby. Don't let it stress you out.

12lb8oz.... OUCH

ChristineBaker23 · April 2014

After reading these I feel much better. My external measurement has been ahead by 2 cm since about 25 weeks. They did an ultrasound at 32 weeks for "excessive fetal growth" and our bouncing baby girl measured in the 94th percentile at an estimated 4.6 lbs. they were not concerned in the least by this and didn't adjust my due date or anything. That being said I am now terrified to deliver a ten pounder but hearing so many people say their estimates were wrong makes me a little less freaked out. I digress... Anyhoo, the doctors seemed more concerned with making sure baby has enough fluid and that she measured evenly and there were no abnormalities. I have another ultrasound at 37 weeks to check her growth again.
Also I wouldn't let your husband's
current size be too big a factor. My brother is 6 foot 9 and weighed 6 lbs at birth. I am 5 foot 5 and weighed almost 9 lbs at birth. We were both full term.

irenewslee · April 2014

I just think that it is what it is. At this point, we can only hope the baby's head isn't TOO big and shoulders aren't TOO broad so the delivery won't be TOO painful. There isn't much we can control so I think we should just relax at this point. I was measured 2 weeks ahead during my anatomy scan at week 19 (that was the last time I saw my baby). I got people telling me my bump looks big and others telling me they can barely notice. Oh well... Life will never be perfect.

Mztwilson · April 2014

With ds they did an ultrasound the day before he was born at 32 weeks the ultrasound tech said he was 4lbs 8 oz. and sure as shit he was born 4lbs 8oz.

MrsCase1 · April 2014

I heard a really good analogy about their estimating just this morning. It is the equivalent of seeing someone from far across a room and trying to guess their height. Basically you might guess 6 foot 2 but really they're 5 foot 8.

My doctor doesn't put much stock into those estimates. She mainly looks for abnormalities. One tech predicted my son would weight close to 9 pounds but he was 6.11.

enpowers · April 2014

This May be a stupid question, but is a baby's length ever a huge concern? The only reason why I ask is because I am 6ft and DH is 6'8 and at our 32 wk scan they estimated him at 6lbs (which I know isn't super accurate) and 19in. He has always measured a month ahead of schedule, and my SIL's baby was 23in long....that seems like an awfully long baby! Almost two feet of baby curled up in my shit freaks me out.

RaeJ004 · April 2014

enpowers said:

This May be a stupid question, but is a baby's length ever a huge concern? The only reason why I ask is because I am 6ft and DH is 6'8 and at our 32 wk scan they estimated him at 6lbs (which I know isn't super accurate) and 19in. He has always measured a month ahead of schedule, and my SIL's baby was 23in long....that seems like an awfully long baby! Almost two feet of baby curled up in my shit freaks me out.

I don't think so. I'm 5'2" and DD was 21.5inches. They are pretty squishy and can curl up in a tiny little ball.

enpowers · April 2014

Omg @LoHerrim‌ that's pretty long for 37 weeks

do you think that has anything to do with you going early at 37 weeks (if that's okay to ask?)

katekat8721 · April 2014

enpowers said:

This May be a stupid question, but is a baby's length ever a huge concern? The only reason why I ask is because I am 6ft and DH is 6'8 and at our 32 wk scan they estimated him at 6lbs (which I know isn't super accurate) and 19in. He has always measured a month ahead of schedule, and my SIL's baby was 23in long....that seems like an awfully long baby! Almost two feet of baby curled up in my shit freaks me out.

I haven't heard anything about it being concerning, and our girls are quite long in here too (I'm 5'11" and dad is 6'2"). It is kinda freaky to think about!

ChristineBaker23 · April 2014

katekat8721 said:

enpowers said:

This May be a stupid question, but is a baby's length ever a huge concern? The only reason why I ask is because I am 6ft and DH is 6'8 and at our 32 wk scan they estimated him at 6lbs (which I know isn't super accurate) and 19in. He has always measured a month ahead of schedule, and my SIL's baby was 23in long....that seems like an awfully long baby! Almost two feet of baby curled up in my shit freaks me out.

I hadn't thought about that equaling almost two feet wow. I imagine this is why their bones are so soft when they are born. In my ultrasound at 32 weeks my daughter had her feet by her head playing with them. And i mean like it was right by her ear. I wish I had the pic on my phone to share. It was adorable but it also kind of shocked me she could do that in such a tight space haha. They are very squishy and flexible.

chickpea912 · April 2014

Just thought I'd add in these stats since I was looking for M's estimates - yesterday at my growth ultrasound (I'm 34w today), baby was measuring two weeks ahead and was estimated to be 6#7oz. Limbs seemed to be in the average range, whereas abdomen and head were huge. I wasn't super surprised, as M had/has a big ass head, and I still get a kick that I have these bigger babies despite having - this time - two different factors that could cause growth issues.

So, baby was estimated to be at 6#7oz. With M, at about 33w4d, she was estimated to be only about a week ahead and roughly 5#3oz. I went back to my old blog, and right around 37w6d (a week, to a week and a half before my induction/c-section), my last growth ultrasound with her put her at 7#9oz. She was born at 8#5oz, so not too terribly far off.

Just one piece of anecdotal evidence regarding the accuracy (or not) of growth ultrasounds.

KristiKubic · April 2014

Thanks everyone. I am not necessarily concerned too much as I have been planning for a bigger boy all a long. I was just curious as to others experiences. My doctor is not too concerned either she thinks I am going to have a healthy baby and feels I will be able to deliver just fine. I am going to continue with my birthing plan of going all natural and not let his size interfere with that. I am open to interventions if and only if he is negatively impacted at some point then I obviously want him here by whatever means necessary.

To compare to my mom and sister....I was 8lbs 12 oz and my sister had a 7lbs and her youngest was close to 9lbs and is a peanut now! I guess we will see in the next 4 weeks!

justme04 · May 2014

With ds2 I was told at my 38week ultrasound he was measuring at a little over 8 pounds. The next week when he was born he came out at 9 lbs 4 oz. I'm already concerned this is going to be another big baby. At 32weeks they estimated her weight at 4 pounds 15 oz. That's already more then ds1 weighed when he was born at 34 week gestation.....looks like he is the only one of my kids who would have hit an average birth weight had he stayed till term. I don't get it though. I haven't put on a lot of weight, I eat really well, don't have GD (which everyone just assumed had been the cause of ds2's weight), and DH and I were both 7 pound babies. Seriously though after the tech told me little girls weight estimate I said I was glad I already planned for the csection. Pushing DS2 out was painful and cause the worst level of tearing.

MrsAMB07 · May 2014

I wouldn't worry too much about the growth ultrasounds estimates. They estimated my one nephew to be 6 lb. and he was over 8, and his brother to be 8 and he was 6. I've heard of that happening quite often.

As far as your husband's build, while it may be a factor, it certainly isn't a definite thing. My husband is a similar build as you described yours and both he and his father were 9 lb. babies. Mine have both been in the 7 lb. range. My son was 90th percentile from there on out... grew like crazy, but it wasn't an issue at birth. I hope for your sake it's the same!

Lynnja616 · May 2014

I had a growth u/s with DS because they suspected I was having a big baby. They estimated by birth he would weigh 9 lbs 8 oz and he was 9 lbs 5 oz so for me, it was pretty darn accurate.

katekat8721 · May 2014

I just asked at today's growth scan and the margin of error for our place is +/- 10 ounces.

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