3rd trimester scan accuracy

[Herchy]

Hi,
I was just wondering if anyone had any info on the acutal accuracy of 3rd trimester scans. I know that they are supposed to be more inaccurate than early scans, but would love to read some nice conrete evidence if anyone knows where I can get it.

Cheers in advance

[Flashdance]

Hello!
Do you mean accuracy in estimating the size of bubs??

[Herchy]

Yes, size wise
I am apparently having the world's largest baby, even though she is measuring less by scan than DS at this stage and noone was concerned then.

[maisymum]

.......Try not to worry yourself too much about it....last pregnancy i was told i would have a 8 1/2 pound plus baby but he ended up being 6 lbs 14 ozs..........

[teenie]

Hi Herchy,

I am sceptical of the accuracy of 3rd trimester scans. I had one last time at 36/37 weeks as I was apparently having the worlds smallest baby...that scan said around 5lb...he was born 2 weeks later: 6lb5oz. I think women all carry diffferently. I am looking very small for dates again this time - it's just me!!!!!

[lovelymum]

I had a series of scans in my 3rd trimester with DD as she was measuring small on the first scan at around 29/30 weeks she was in the 50th percentile for her growth rate, 33 weeks she dropped to the 30th percentile and at 36 weeks she was at the 20th percentile - she was born via emergency c-sect the next day!! But the scans did positivly show a decline in her rate of growth and they also showed a decrease in amniotic fluid and blood flow thru the placenta the scan however estimated her weight to be a bit heavier than it was I think 6 pound something but she was born 5 pound 5 ounces. My ob ordered the scans as I had the same problem with my first pregnancy although I only had two scans in my third trimester but again it estimated he was in the high end of 6 pounds and he was born 5 pound 4 ounces. Hope this helps

[Flashdance]

I had a scan at both 32weeks and 36 weeks and bubs was estimated at more than 4kg, so was induced early at 38+4weeks, and bubs was only 3.2kg!

Everyone who performed the scans was saying how big bubs was, I was freaking out! I wish I had read here on BH how often they get them wrong, could have saved myself some worry!

[shaz77]

I was concerned about the size of my first being big (I felt ssooo heavy!) and the doctor said not to worry - it will be about average (7lbish) but he was 10lb 4oz (4.65kg!) so with DD they kept saying oohh, big baby and I was induced 2 days before my EDD she was 9lb 2 oz (4.15kg) so I'm glad they didn't make me go 10 days over!!

As for the scans, I believe there is a 10% margin of error on 3rd trimester scans so they wouldn't induce me with DD if I wasn't over the 90th percentile.