U/S measurement vs reality?

10-4LilBuddy

At my growth scan yesterday, baby boy measured 5 lbs and baby girl measured 5.5 lbs. Since he is in the 13th percentile, we moved up my C section by a week.

I read on Dr Google that ultrasounds can be off by as much as two pounds. What is your experience? I couldn't imagine they could mix up a 3 lb with a 5 lb size.

smscartozzi

I just asked the MFM yesterday and he said if you have a good tech the variance is about 10%. So my babies were 4lbs 10oz....he said they could range about 4-5lbs.

ktjruss03

I had a growth scan the day before I went into labor and it was off about 1/2 pound for both babies.  I have heard of them being off by a lot more than that though.  I do think it depends on the u/s tech and how they measure.  I had one tech tell me that she always measured babies on the bigger side. 

24karat

With DD they said 8lbs, give or take 1.5lbs. She was 6.14 at birth. The twins were within 3oz of their estimates. Both growth u/s were done by the same person.

1+tripsmom

With my trio they told me at 33.5 weeks they were all A was like 4.5, B around 4.13 and C about 4.10 they were born at 35.3 weeks and were 4.5, 5.2, and 4.10 so either they did not grow or they were off. I don't remember the exact numbers just no super close or the same as birth weight over a week later.

ks3pink

With DD they said she would be no more than 5 lbs, she was 7 lbs 4 oz. With the boys they said they were going to be well over six lbs each, more in the seven to eight range. They were 6 lbs 3 oz and 6 lbs 6 ozs. I don't trust ultrasounds much for weight!

lsmith0917

I had an ultrasound the day before I had my b/g twins. They were estimated to be 6lbs 7oz and 6lbs 8oz....they were born 6lbs and 6lbs 14oz so about a 1/2 pound off in either direction in my case.

caden

My last one was about a half a pound off for each baby. My babies were smaller than what they measured.

Lil Kate

One of my singletons was estimated to be 10+ lbs at 37 weeks. When I delivered at 37 weeks 6 days he was 8 lbs 3 oz. I wouldn't trust an ultrasound. Also my whole pregnancy baby a measured larger than baby b. at birth baby b was actually 5 oz larger.

SWA80

I had growth done the day of my c section and they were only a few ounces off for each.

SwetaV

Our measurements were off by 1/2 lb on DS and almost a pound for DD.

Jess63085

They can be off. My niece was estimated at 6 lbs and she was 8 lbs, 4oz at birth. At my 35 week growth check, my twins both were estimated at 5lbs, 13oz. They were born 3 days later...my son was 5lbs,10oz and my daughter was 5lbs,8oz.

megs2011

I had a growth scan at 32 or 33 weeks (I can't remember now) but they estimated them at 3lbs and 3 1/2 lbs. They were born at 34+4 and born at 2lbs9oz and 3lbs7oz. So my estimates were close.

Mrs.Guz

At 37w2d, they predicted baby A to be 4#13oz and baby B 6#11oz. They were concerned about the discordance and the fact that A was measuring so small. I delivered at 37w4d and baby A was 5#3oz and baby B was 6#2oz. So not nearly as much of a discordance between the two and A was not as small as they thought but still pretty close.

Jfila13

DS was estimated to be in the "high 8s." He was 10 lbs 1oz.