But how accurate are they really?

allisshiney · February 2016

Ok Mama's! I just had an ultrasound at 31+3 and the tech thinks this baby is huge. 5.1lbs and in the 97th percentile for size. She says the can be a + or - 1lbs discrepancy but I've heard of other woman say their numbers were waaaayyyy off. Can you reassure me stories of inaccurate ultrasounds? I'm aiming for a VBAC.

CCLow87 · February 2016

I've always heard it can be + - 2 pounds. So baby could actually only be 3.1 pounds. Also, you'd have to check, but I don't think a big baby actually affects your chance of rupture during a VBAC. I know several people who have had elective sections for big babies that weighed less than 6.5 pounds.

fourtsixand2 · February 2016

I have no personal experience, but all 3 of my sister's kids were supposed to be "huge babies". Her first was 6lbs, and the last 2 were roughly 7lbs each. So, not "huge babies" by any means.

AmadorRose · February 2016

There was a post several weeks ago about ultrasounds being off by up to four pounds. I wouldn't let one tech scare you out of a vbac if that's what you want. If it doesn't work, at least you tried.

AnnikaD20 · February 2016

I was supposed to have a huge baby (well over 10lbs they said) and he was born full term at 7lbs 4oz. So... yeah, it can be off. Way off. (Also, women give birth to big babies without complication all the time.) Keep going for your VBAC if that's what you want.

kyraaD · February 2016

*lurker from March*
they're really quite inaccurate. they can be +/- 2lbs off. I've heard of a lot of cases where moms have been told they're having huge babies, & then they end up being an average or even smaller size. try not to worry!

runningwild · February 2016

My best friend just vaginally delivered a 10lb 4oz baby boy and she's a small girl! Don't let them scare you

Lilpenguin3 · February 2016

They til

Lilpenguin3 · February 2016

They told me I'm measuring 3.5 weeks ahead and she's probably already 4lbs. The same thing happened to my friend a few weeks ago and she delivered late and the baby was 10lbs. She delivered uneducated and it was her second.

seasidesweete · February 2016

With DD I was late so they did an us at 41 weeks. Said she was 8lbs 1oz. She was born 2 days later and was 7 lbs 12oz. So it wasn't that far off. But i had always heard they can vary and they had even told me that that day. It may depend on the angles they get the measurements from and all! Like others said people have bigger babies w out complications all the time go for your vback if ya want it!

yodiggity · February 2016

https://www.huffingtonpost.com/entry/doctors-may-be-telling-too-many-women-youre-having-a-big-baby_us_569400c7e4b0cad15e65ae65?ir=Women&section=women&utm_hp_ref=women

Daniep08 · February 2016

It was actuate with both my kids so far. With my daughter in was measuring 3-4weeks ahead and based on my ultrasounds and them saying the baby gains a half a pound a week she would have been 10lbs at birth and that's exactly what she was! And her delivery, birth and recovery was way easier than my 7lb 10oz son!

Missingchampagne · February 2016

Daniep08 said:

It was actuate with both my kids so far. With my daughter in was measuring 3-4weeks ahead and based on my ultrasounds and them saying the baby gains a half a pound a week she would have been 10lbs at birth and that's exactly what she was! And her delivery, birth and recovery was way easier than my 7lb 10oz son!

Was your daughter 3-4 weeks ahead the entire time, on each ultrasound? Or did this measurement change throughout the pregnancy?

cosmobella · February 2016

Mine were pretty accurate. Since I am high risk I have had monthly growth u/s with the high risk group throughout all of my pregnancies. This time they get bumped to every 3 weeks in the 3rd tri. They take measurements to estimate the baby's size and this trumps the fundal height estimate which has always been high. My first was estimated to be 8-9 pounds and was 8 pounds, 7 oz and I ended up with a failed induction c/s at 40 weeks and 2 days. My second was estimated to be over 10 pounds. I was trying to VBAC as well but ended up with another c/s since I didn't go into labor by my due date with high risk status and they don't induce after a c/s. He was 10 pounds, 8 oz also born at 40 weeks and 2 days. I'm not sure what would have happened if/when my body gone into labor on its own.

I hope you get your VBAC but try to come to terms with the possibility of it not happening. When I reluctantly went in for my 2nd c/s I had been contracting all day. The doctor put me on the monitor and confirmed that I was having some serious contractions that might amount to something. I left my planned c/s to go home and see if my contractions turned into labor. The contractions stopped hours later that night and I was rescheduled for the c/s the next day. I was in a much better state of mind going in the next day knowing that I had tried to get to that delivery on my own, despite the idea that DS was big and fear of shoulder dystocia. But I also accepted that my doctors had my best interest in mind.

I'm small in stature (5 foot, 1) and despite making plans to VBAC I think I am happy my big baby was born by c/s. I had all kinds of thoughts about what my body could do if I had had the chance (and still wonder) but I have no idea when I would have gone into labor (seriously, what the hell was my 10 and 1/2 pound baby waiting for?!) and if the VBAC would have worked out. At this point I trust my u/s results because they've been accurate in the past for me.

helleebellee · February 2016

At 38 1/2 weeks, but son was measuring in at 5lbs. They decided it was IUGR and we induced. He was 6lbs. That's my only experience with measurements.

Goldsgirl9 · February 2016

My SIL was told her kid was going to be over 9lbs and he was just about 7lbs. Her OB kept telling her she was going to have a huge baby for weeks on end and he couldn't have been more wrong. Thankfully my OB doesn't go based off ultrasound alone.

korpatch · February 2016

Ok... So what does the percentile mean? Yesterday I was told he's measuring perfect to the day and in the 45% for height and weight.

erind228 · February 2016

My three babies have been 9 lbs even, 9.12, and 9.10. I delivered all vaginally without complications. So, even if your baby is a little bigger than normal it's not that huge of a deal. I personally like my big babies....they don't feel so fragile to me.

yodiggity · February 2016

korpatch said:

Ok... So what does the percentile mean? Yesterday I was told he's measuring perfect to the day and in the 45% for height and weight.

45% is pretty close to average. Average being 50%. If your baby is in the 45%, he is 5% smaller than the average baby at that time point in gestation. They typically don't seem to mind til they're getting close to 10%, from what my doctor said to me (not sure where they draw the line on the big side of the scale).

wildtot · February 2016

Lilpenguin3 said:

They told me I'm measuring 3.5 weeks ahead and she's probably already 4lbs. The same thing happened to my friend a few weeks ago and she delivered late and the baby was 10lbs. She delivered uneducated and it was her second.

At 29+6 I was told the baby was measuring 2-3 weeks ahead and around 4.2 lbs. He's been measuring ahead since early second tri.

mrstrax · February 2016

DD was within an ounce of their estimate when she was born ~36 hours later, but she was on the small side (6#3) and I had low fluid levels, so idk how that affects readings. I'd assume the +/- 1lb is true and still go for your VBAC until your doctor says it's not safe for one of you.

thaisac1 · February 2016

korpatch said:

Ok... So what does the percentile mean? Yesterday I was told he's measuring perfect to the day and in the 45% for height and weight.

A percentile means how one measures/ fares in comparison to the normal distribution of a particular topic.
The mean represents the 50th percentile (which means the smack down the middle average ... in the example of weight, if a baby is in the 50th percentile, he is heavier than 50% of babies and lighter than the other 50% of babies for that gestational age).
If your baby is on the 45th percentile (so is mine BTW), this means he is heavier than 45% of babies, and lighter than 65% of babies at that gestational age.
If a baby is on the 80th percentile, this means he is heavier than 80% of babies, and lighter than 20% of babies at that gestational age.
And so forth...

AnnikaD20 · February 2016

yodiggity said:

korpatch said:

Ok... So what does the percentile mean? Yesterday I was told he's measuring perfect to the day and in the 45% for height and weight.

45% is pretty close to average. Average being 50%. If your baby is in the 45%, he is 5% smaller than the average baby at that time point in gestation. They typically don't seem to mind til they're getting close to 10%, from what my doctor said to me (not sure where they draw the line on the big side of the scale).

That's not quite right. 45th percentile means that your baby is bigger than 45% of other babies. You are absolutely correct that it's close to average.

Andie41 · February 2016

My DD was estimated to be between 7-8lbs and was less than 7 a week late. They are notoriously inaccurate. I'm sure you'll get your VBAC.

littleredx2 · February 2016

Last pregnancy, I started measuring bigger at 31 weeks by fundal height so I had a couple of growth ultrasounds. The first one at 32 weeks said he was already 6 lbs (which I don't think was likely due to his size at birth at 40 weeks). The last one I had measured him at 8.3 lbs and he was born the next day at 9.3lbs so the +/- one pound was accurate for us that time. Don't neccessarily be scared of a big baby though. My Dr. had me a bit freaked out but all went really well and it was an easier recovery than DS1 who was only 7.6lbs at birth.

Also keep in mind, the way they are guessing weight is by measuring head, belly, and femur. So if you have a tall baby, they could assume larger. Or if your baby has a bigger head, that will assume bigger baby. My sister was told that her guy would be huge at birth, 10+ lbs. He was born right at 40 weeks weighing only 8 lbs even but did have some crazy long legs.

HDakota · February 2016

MFM told me last week that at best, estimates of weight after 30 weeks are about 35% accurate. This was in response to my concern that she would induce me because my baby is "too big." I have GD, so they are monitoring me closely and OB really scared me, saying they would induce as soon as MFM says he is big enough. She said absolutely not BECAUSE those estimates are not reliable. Go for your VBAC if that's what you want to have!

Daniep08 · February 2016

Missingchampagne said:

Daniep08 said:

It was actuate with both my kids so far. With my daughter in was measuring 3-4weeks ahead and based on my ultrasounds and them saying the baby gains a half a pound a week she would have been 10lbs at birth and that's exactly what she was! And her delivery, birth and recovery was way easier than my 7lb 10oz son!

Was your daughter 3-4 weeks ahead the entire time, on each ultrasound? Or did this measurement change throughout the pregnancy?

She was pretty much ahead the whole second half/3rd trimester. I don't remember when exactly it started.

3dogs_and_a_baby · February 2016

At my 30 week ultrasound i was told DD weighed 3.10lbs, at my 20 week she was measuring bigger too (at least according to all of the apps that I have). One of the dr in my practice said it's totally normal because I told her I was worried about her being so big already. At my 32 week check up last week another dr told me not to buy newborn clothes bc I'ms having a big baby. They will do another ultrasound at 36 weeks to get an estimate on how big DD will be. I was 7.13lbs when born and my husband was 7.10lbs so we were both average size babies and from what i've read the baby usually weighs close to what the parents did.

To this day I think that my dr got my due date wrong, according to last period my due date should be sooner than the one that they gave me. However my dr wont change it unless they think they baby will come over a week sooner than what they gave me. DD has already dropped a decent amount this week, so i'm hoping that i'm right and she will be arriving sooner. I'm also already really uncomfortable and contemplating starting my maternity leave sooner unless this discomfort starts to ease up a bit.

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