Anyone have ultrasound to predict weight/size? Was it accurate?

[heatherly2475]

How long before delivery did you have it done? I was told yesterday my OB wants to do an ultrasound to evaluate the size of the baby. They think he had a sudden growth spurt and I'm guessing they're a little concerned he will be too big. I'm 37 weeks tomorrow and the dr. thinks he's already 7 pounds. Induction and pitocin were mentioned and of course I didn't like that at all.

[pilldoc]

I had an ultrasound at 36 weeks. At that ultrasound the baby was measuring small. So I have had an ultrasound every week since. They have done a BPP (Biophysiologic Profile?) every week. Happily I can say that DB is growing fine. She is now up to an estimated weight of 6 lbs 10 oz. I don't know how accurate the estimate is yet though. Yesterday was my due date and still no bundle of joy yet. If I don't have her by 41 weeks I will be induced. Like you I am not looking forward to the Pitocin ! I will let you know how good the estimate was. I have heard that they can be off by a good bit. Good luck!

[sugarsnappea]

It seems odd to me that they would be exploring the issue of induction at 37 weeks...

I had my last US at 41 1/2 weeks and it guessed my baby to be 10# 8oz. Well, my DD was born 3 days later and was 8# 10oz. This US "guess" was the last determining factor for my emergency C-sect. In my experience the results were not reliable.

Good Luck! :)

[heatherly2475]

All the concern seems odd to me as well. She didn't sound as though she was anxious to induce me now, but it seemed that she wanted me to know that this is a possibility we may have to deal with later. From all I've read, it seems that 7 pounds at 37 weeks isn't that abnormal; most of what I've researched indicates the baby should weigh 6 to 6 1/2 pounds. So 7 doesn't seem so off base to me. And if the baby gains 1/2 pound each week from here forward, that's still only 8 1/2 pounds at 40 weeks. I have friends who have delivered 9+ pounders with no episiotomy! I'm going to gather more research and I will have lots of questions at my appointment next Thursday. Thanks for all the input.

[Calmegja]

Two of my last day ultrasounds were spot on on size. They estimated Jake at 6 pounds 11 ounces at 37 weeks, and when he was born he weighed exactly that, 5 hours later. The same with Josh. His estimate was exact as well.

The girls were off by 1.5 pounds each.

I think it's a good guide, but far from exact......

[kransden]

My ultra sound was 1 week before delivery and was off by an oz which was to be expected. Babies do grow! I think it depends on the tech. I was at a high risk place and the tech had a lot of experience.

Karin
Katie 10/24/02

[atlbaby]

I had a number of estimated fetal weight U/Ss from about 27-35 weeks because my OB was concerned the baby was too small. They showed that she was growing, but that she was pretty small. By my last one at 35 weeks the U/S showed her weighing in at about 5.5# so my dr was satisfied. But 4 weeks later I delivered her and she was 6#11oz! So it was really me that was small, and not Arielle! Since I've had an even harder pregnancy this time and am not showing much I'm hoping that my OB will remember that Arielle was fine and not send me for so many U/Ss!:)

-Rachel
Mom to Arielle Jill, 10/30/01
#2EDD 10/24/03-Another Girl!:)

[pritchettzoo]

I had this done at 30 weeks because I was "measuring" (you know, with the super-scientific plastic tape measure...) 35 weeks. My dr's office has an u/s and technician in office, so we just had to wait an hour or so to be fit in. The technician not only measured the baby, but she also measured the fluid around the baby. If either had been too voluminous, it could have meant a problem. My doc said if she had been measuring large, they would keep track of her growth more carefully and *offer* me an induction/scheduled c-section and not let me go 2 weeks late. I think she said what excess fluid meant, but I can't for the life of me remember that part. It was only 3 weeks ago...how sad!

From all the research, ultrasounds are safe, so enjoy the opportunity to see your little guy! Maybe you'll get a good shot of his sweet chubby baby cheeks!

Anna
#1(DD) EDD 9/10/03

[mharling]

I applaud you for researching and being prepared to discuss this with your ob! I too think it's odd that they would talk induction at this point. I agree that 7 lbs doesn't seem completely off base.

FWIW, I had 2 additional ultrasounds at 28 and 34 weeks because I have fibroids. At the 34-week US, the dr was concerned that the baby was small and wanted me to have weekly NST's and another ultrasound at 37 weeks. The dr at the US was the ONLY one who ever thought the baby was small. My tummy was measuring almost 1 cm per week at my regular ob appts. The nurses, my ob, 2 other ob's I saw AND the dr who did the 37-week US did not think that the baby seemed particularly small. Ds was born at 40 weeks at 6 lb, 15 oz. Not huge, but certainly not on the small end to be concerned about.

So, what's my point here? I think that my 37-week US and the weekly NST's were not necessary. I honestly believe it was a CYA move on the part of the doctor. And, in these times when insurance is already expensive and rising, I am troubled about the additional expense of this. In my case, I would not have even had the 34-week US if I didn't have fibroids and my ob would not have requested a 37-week US. Sorry for the rant, but the bottom line is I think you are wise to be suspect and gather as much information as you can. If something like this comes up for me in future pregnancies I will definitely handle it differently.

Oh, and to answer your question, the 37-week US was pretty accurate in determining the size. I don't remember the details, but it wasn't very far off.

Mary & Lane 4/6/03
http://www.shutterfly.com/osi.jsp?i=67b0de21b3237413c427 - New 6/18

[lizajane]

i gave birth to a 9lb 91/2 oz, 22 inch long baby boy in 11 hours of labor, with 30 minutes of pushing. it angers me that OBs want to talk induction or c-section because "you may have a large baby." thank goodness for me, the OB thought he was 7-7/12 lbs while i was in labor. if he had known that he was going to be 9.5 pounds, he may have tried to talk me out of a vaginal birth. there was NOTHING wrong with my big baby and there was NOTHING wrong with me (after a few stitches.) Don't let it worry you too much. evaluate the obs advice carefully so that you don't take any unnecessary risk for you or baby, but remember they are often quick to go to induction or c-section when it isn't necessary. (and my baby was 8 days early, on his own. he knew he needed to come out!)

[sweetbasil]

My ultrasound at 36 weeks was pretty close at predicting Charlie's weight- he was actually a little bigger than expected when he came out at 38 weeks.

Best wishes!

[amp]

I had many ultrasounds during my pregnancy, and toward the end, the we were sure that this was a large baby, and the doctor had told me early on that I had a small pelvis. She was concerned about my ability to safely vaginally deliver a large baby. I had an ultrasound at 38 wks to estimate fetal weight. They estimated him to be 10 lbs 15 oz. I didn't really believe this, but my OB said she didn't expect this estimate to be off my more than 1/2 lb. She was right. When I had a C-Section 1 wk later, my son was born at 10 lb. 9 oz.

[stillplayswithbarbies]

I had ultrasound at 39 weeks and they said baby would be over 10 pounds. Twelve days later, she was born at 8 lb 6 oz. Ultrasounds are even less accurate for women who are overweight.

...Karen
Jacob Nathaniel Feb 91
Logan Elizabeth Mar 03

[kohlbacher]

My u/s seemed very accurate - except for the last one - but his femur measurement was larger than the machine allowed, so we weren't surprised.
20 weeks: 1 pound even
29 weeks: 4lbs 7oz
37 weeks: 8lbs 12oz
41 weeks: 8-9 lbs?!! But, my dr. also knew this was off and estimated the baby to be 10lbs 8oz - at 2 days shy of 42 weeks, he was forcibly born - and was EXACTLY 10lbs 8oz!!!!

*Inducing is NOT fun. I would recommend trying to avoid it if there aren't any health issues. I did end up needing a C-secion, but at 40 weeks, I hadn't even started to dilate yet - so inducing earlier really wasn't an option. As my dr said at 40 weeks, he's big now, he'll be big later!

*I wanted to add - I did labor and the baby did get stuck. But, I was so glad to have an OB that would allow me to try. You never know what your body can do unless you try. I had the last 2 u/s since we wanted to make sure that the head measurement was larger than the chest - so shoulder dystocia wouldn't be a concern. Had the chest measurement been larger, my OB told me she wouldn't have been comfortable with letting me try a vaginal birth.

[nathansmom]

I had ultrasounds at every visit. I had one just hours before an induction and was told the baby was 8lbs 10oz. He was born less than 24 hours later and weighed 8lbs 14 oz. I think it all depends on how good the doctor/tech is at reading ultrasounds. I don't know if it makes a difference but I did have the new ultrasounds all throughout the pregnancy.

[chrissyhowie]

Ultrasounds really are not that accurate in estimating fetal weight. It depends very much on the person doing the actual sonogram and can vary widely.

Fetal macrosomia (large baby) is best defined as an estimated fetal weight (EFW) of >4500g (9.9lbs). About 10% of all infants weigh >4000g (8.8lbs) but only about 1.5% will weigh >4500g. The reason why fetal macrosomia becomes a concern is that when the EFW is >4500g, the risk of shoulder dystocia (the shoulder getting stuck after delivery of the head) has been found to range from about 10-25%. If you are also diabetic, the risk rises to about 20-50%.

That being said, ultrasounds are not a great way to predict fetal macrosomia. They are very good at predicting that fetal macrosomia is NOT present (~98% negative predictive value), but are definitely much less accurate at predicting that it is present (~40% positive predictive value). The only real way to diagnose fetal macrosomia is to weigh the baby after it is born!

Currently the medical literature does NOT support early induction of labor for suspected macrosomia. In the studies done, this indication for induction at least doubled the rate of c/s without reducing the rate of shoulder dystocia or newborn morbidity.

There are also several large studies which demonstrated the safety of a trial of labor for those with EFW of >4000g.

Like you mentioned, 7lbs is not at all dangerously large or anything like that for a 37 week pregnancy! In one way, maybe it was a good thing that your OB mentioned induction and pitocin this early so that you could give yourself some time to learn more about everything :). Even with all the info out there, remember that every pregnancy is different. The plan that is best for you will depend on your own unique situation. It is always good to ask lots of questions and make sure you feel comfortable with the responses. Sorry the above post is so lengthy, but I hope it provided you with some info.

[Board Baby]

Board Baby

I was induced at 35 weeks due to a condition that I had -Obstetric cholestasis. It is a weird condition that affects your liver and bile salt build up and if the baby is not born early they are often still born. You itch 24/7 everywhere. Anyhow at 30 weeks I got the symptoms and they started doing ultrasounds on a weekly basis so they could predict when to safely induce the baby. They figured the baby was 6lb 2 oz (4 days before I gave birth)and she was born 5 lb 5 oz. Induction wasn't a fright I had a great mid-wife (yes it was a hospital birth) plus I had an obstetrician- we walked lots during labour and I made a 20 page birth plan and the hospital staff actually read it and for the most part respected it. Make sure that you walk lots if induced and I suggest that you read the Dr. Sears and Martha Sears information on birth. They are just so common sense and informative. If you have a doula or mid wife they will use massage and warm cloths to avoid episiotomy, which is out of favour in a lot of regions now. The best advice is ask lots of questions, arm yourself with lots of info and I highly recommend a doula. Oh yea and the other bit of advice my mid wife gave me- if you are going to have your baby early or be induced have lots of sex, it supposed to be good for getting the hormones going and your body ready for birth.

Good luck,

Lynn

[JElaineB]

I had several ultrasounds throughout my pregnancy. The last one to check for weight was four days before my due date. They estimated the weight at 5 1/2 pounds, which was way too small for my doctor's liking (plus the baby was dropping in percentiles). So I was induced and ended up having the baby by c-section on my due date. He weighed 5 lbs. 6 oz. so the ultrasound was very accurate. Even so, don't go through the induction just because they "think" your baby is big. People have big babies all the time. My body wasn't ready to have my babe and the induction was a nightmare (and didn't work anyway).

Jennifer
mom to Jacob 9/27/02

[redhairedgirl]

I had an u/s at 38w6d... they predicted him to weigh 7 pounds at that point.
He was born 40w3d and weighed 7lbs 12 oz. :)

[Melaniee]

I had two at 34 weeks and they estimated my son was ~6#. He was born 7lbs 8oz at 40 weeks.

I really wouldn't induce if you don't need to. It seems women often end up with a c-section b/c the baby is just NOT ready until they are ready. If your baby is too big and you end up with a c-section anyhow, at least you waited until they're fully "cooked" and ready to be born.

Also, if your baby is going to be big, you might want to try laboring in positions other than flat on your back, such as squatting, to help open your pelvis more.