How accurate are ultrasound weight measurements?

Question

I had an ultrasound done yesterday and the Tech said my baby was weighing "around 5Ibs" . Before my ultrasound my Dr. said baby was measuring little but not to small.. im hoping she won't be to big or too small. Due to me being high risk pregnancy there hoping I deliver around 37-39 weeks if not I'll be induced before 40weeks...I still have a few more weeks to go. How are techs even able to estimate how much the baby weighs? Has anyone ever had there baby weigh close to what was estimated for baby's weight?

Answer

With my first I was induced at 39 weeks, before they sent me over they did growth scan and said he would be 8lbs 11oz- 9lb 
He was born 8lbs 1oz after 3 days of laboring on Pitocin. He was super swollen from all the fluids they had me on, so technically he would've been 7lbs something.

Answer

Research has found late term ultrasounds to be wrong on weight estimations 50% of the time and they are statistically linked to a higher cesarean rate.

Answer

They are not accurate. And I personally would never put faith in a 3rd tri ultrasound to determine whether or not I need induced or a c-section. I had an ultrasound at 36 weeks to check baby's position he was breech, then transverse, then oblique, and finally head down! The weight estimate at that time was 6.5lbs. But my midwife said that his actual weight could be a pound or more different either way.

Answer

I think they estimate the weight by the measurements of the anatomy x

How accurate are ultrasound weight measurements?

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