How accurate are growth scans?

[starshaker]

Just that really.

I've been told they can be as much as 5 days out. My latest scan put my due date 4 days earlier than the last one which has to be wrong as that would mean I conceived a week before I had IVF!

I mean growth scans. The scans that tell you how much your baby weighs at the time

oh lol, not got to that stage yet.

I didnt have it with dd but since its twins this time im getting lots of scans. Last time my boy was measuring 4lbs and girl 3lbs. Just wondered how accurate it was likely to be

I had some with dd, as ds1 was big. At 37 weeks, they had her down as over 10 lbs When she was born (39 weeks) she was just over 8lbs, so in my case, it was way out.
I have heard that it's more accurate with smaller babies, but I can't remember where I read that!

Mine with dd were way out. Like tutusare4, they were predicting a plus 10 lb whopper and I was terrified what the labour would be like!! In fact, they induced me at 38 weeks, because everything (bump measurements and scans) was pointing towards such a big bubs! Then I was pleasantly surprised that girly was a petite (!) 7lb 14oz- smaller than her big brother!! So, in my experience, the way I seemed to hold the bump seemed to be misleading- apparently I have heard that there is quite a lot of variation in sonographic accuracy??!! I was slightly miffed at the time, because I had also been induced with DS. Hopefully this time (newly pregnant again) will be able to have contractions naturally.

They can be a lb out either way and are only accurate at the time they are done

The baby can have growth spurt or slow up after the scan

So..... limited accuracy but a useful guide in decision making?

My DD was apparently 8lb4oz at 36 weeks predicted 10lb and was born at term 8lb1oz.

I had a grwoth scan at 38 weeks and was told my DD was approx. 7lbs11oz. Gave birth at 40+5 and DD was actually only 7lbs8oz.

So its quite possible, if not likely that my twins are smaller than what they think

Yes, or bigger I suppose?

I had one a few days ago -34 weeks because of my increased BMI- also expressed as being fat! Apparently it puts me at 10 days further on than I should be but the head size in the 98th percentile.
My problem with them is that they don't take into account genetics. Both sides of family are very tall with big heads-I dobnt know of any of us that can buy normal size hats. Even my 4 year old is in an age 9 min.
Remember they are only a guestimate and depends greatly on the sonographers skill.