OB's Predicting Babies Weight???

Question

I am 38 weeks with my first and i had a doctors appointment yesterday where my doctor said that my baby was 7 pounds 11 ounces. I was just wondering how often they are right when predicting the babies weight.

Answer 1

With my 1st my ob/gyn guessed by feeling my tummy, that he would be 7 lbs. A week later he was born weighing 7 lbs. 0 oz. 38.5 wks

My midwife guessed, again by feeling, that my little girl was 8 lbs. A week later... 8 lbs 3.5 oz. 38 wks

So, in my case they were right on.
But that is not is so common. I would NEVER use their GUESS as a reason to have c-sec.

Answer 2

Like others have said, weight can easily be off by a pound either way with an ultrasound, so it's not an exact science. And anymore people think a "big" baby is anything over 8 pounds, when in fact that's considered 'average.' I would say a big baby is 9 1/2 lbs or more. And the size of the baby should NOT necessarily determine whether you have a c-section - you can easily birth a large baby vaginally: in fact I've heard women say it's easier to have a vaginal birth with a larger baby. So this is no reason whatsoever to be rushed into a section.

Answer 3

At about 32 weeks, they predicted my daughter would be 11 pounds and started trying to talk me into a scheduled C-section, which I refused.

At 36 weeks in an ultrasound they said the baby ALREADY weighed 10 pounds, 1 ounce and again pushed the C-section. I got them to agree to let me try vaginal delivery first.

My 8 pound, 1 ounce perfectly healthy daughter was born three days later. No C-section required. :)

They probably are often right, but in my case, they were way off. So don't count on it.

Answer 4

It depends on the technician.

In my view, it's mostly luck. I had an ultrasound just over a week before my son was born that predicted him to be around 7.5 lbs at the time and predicted he'd be at least an 8 lb baby at birth. He ended up being just barely over 6 lbs.

In an online parenting community I was in, this same question was polled and most people replied that the weight they had been given had been more than 1.5 lbs off.

It's really just a best guess, not really a technical medical assessment or judgement.

Answer 5

Well, my doctors were right on the money, or pretty darn close, when they guessed my babies' weights!

With baby #1, my doctor told me at about 34wks that he was "good-sized" and I could probably expect to deliver a baby weighing a minimum of 10lbs, maybe more (no, I'm not diabetic.) My baby weighed 10lbs 12oz. (C-section.)

With baby #2, my doctor said I could expect a larger baby as well, given my history, but his prediction was closer to 9lbs. She weighed 9lbs 11oz. (another C-section.)

With baby #3, at my very FIRST prenatal visit at 5wks, my doctor told me straight up, "You ARE going to have a big baby; there's just no way around it." He told me at that visit that I would be having a C-section, unless by some fluke the baby weighed less than 8lbs but he said "I don't see that happening." He was right. He scheduled my C-section 8 days before my due date because he was going to be out of town and didn't want me to go into labor while he was gone. The baby weighed 9lbs 12oz.

So in my experience, the doctors pretty much called it. I guess they have so much experience with feeling around the mom's tummies and everything, feeling the position of the baby, they get to be pretty good "guesstimators."

Answer 6

NO, they are not. We have a friend who was given a cesarean because her baby was "to big". They were predicting over 9 lbs. The baby weighed 7'6". She went through surgery for nothing.

They are usually within about a pound of the actual weight though, but it is just a guess.

PS... of all the moms in my birthing class, not one of the docs predicted the right birth weight, and most of them were off by a good bit.

Answer 7

it really depends on the experience & talents of the DR. Lots of time Dr.'s will try to scare you into induction or c-section by telling you your baby is big. (Usually for the convienience of the provider, not because that is what is best for you & baby.) DO NOT make a decision for either of these procedures based on the dr.'s guess.

Some providers are accurate some are not. (Just like some people can guess how long something is by looking & some can't.)

My midwife is very accurate & her estimates are only off by ounces but she has 20+ yrs of experience & has been proven to give ME accurate weights (5 babies.) Would I chose to have a medical procedure based on her estimates: NO WAY!

Answer 8

My doctor said my daughter was nearing 8 pounds at my lost doctor visit before going into labor. My daughter was 7 pounds 9 ounces. I think that's a good estimate!

Answer 9

According to this site

http://www.dukemednews.duke.edu/news/article.php?id=5870

"Ultrasounds are limited by what they can see. If a mother is overweight or the fetus is in an awkward position, this can throw off the accuracy of such a test. ..."

And this site

http://www.greenjournal.org/cgi/content/full/95/4/502

"Conclusion: Sonograms between 34.0 and 36.9 weeks’ gestation allow for more accurate prediction of birth weight than sonograms later in gestation. "

"Interestingly, sonograms performed after 37 weeks were more likely to overestimate the birth weight of fetuses at risk for macrosomia and underestimate the birth weight of fetuses at risk for growth restriction than studies performed between 34 and 36.9 weeks. "

Here's a more personal conclusion though from this site

http://att.iparenting.com/pregnancy/pictureday.htm

"Ultrasound is reliable at making other predictions, like dating the pregnancy and estimating the baby’s weight. “However, it is important to realize that just like any other imaging technique, ultrasonography has its own technical limitations,” Nazeri says. “For instance, the ultrasound professional’s level of expertise, amount of tissue overlying the baby, and amount of the surrounding amniotic fluid are among the most important factors that can affect image quality and thereby the accuracy of ultrasound in these procedures.”

Jennifer Paul is proof of that. After an ultrasound in the eighth month showed her baby’s weight was average, Paul was allowed to carry to term. Once she was in labor, another ultrasound was performed. The baby was determined to be 8 pounds, 14 ounces. When no progress was made during pushing, Paul’s baby was delivered via Cesarean section. “He was almost 11 pounds!” she says. “For the life of me, I don’t know how those people could have been so off.”

Paul’s story is probably not the norm. Women like Williams and Wingerter were given size estimations that were eerily accurate. And Wingerter’s transvaginal ultrasound predicted the baby’s due date without error. “The ultrasound said June 4,” she says. “My water broke at midnight on June 4.”

Overall I'd say they're fairly accurate, but they can be off. You might ask the dr to do an equation based weight calculation. (see my 1st link) to verify the ultrasound.

Answer 10

It's plus or minus 2 pounds. I do think that some sonographers and high risk doctors are better at predicting weight than the average. Mostly it's because they get the feedback and sharpen their skills. Ask your sonographer if she's ever calculated out her percentage and range of accuracy. They are doing that now at our local hospitals (the sonography is not done by doctors unless they are the high risk doctors). One gal my mom knows has a very tight range (plus or minus less than 1/2 a pound!) over 1000 scans.