Accuracy of CRL measurements at week 9-10 or 12-13 vs LMP?

[tallybee]

Hi!

I'm trying to work out the most accurate dates for my pregnancy.

My LMP was 4th January, on a 27 day cycle, putting that into the NHS due date calculator gave me an EDD of 10th Oct.

I went for a private reassurance scan at what I thought was 9+1 by LMP, everything was perfect and LO measured at 10+1 which gives an EDD of 3rd Oct.

I have my NHS dating/NT scan next week which will be at 12+3 by LMP, or 13+3 by the dating from the last scan.

So my question is, is the measurement from the last scan likely to be more accurate or will they be likely to change my EDD again? Are earlier measurements more accurate than slightly later ones?

The reason I am wanting to know is there's a half price offer on gender scans and I need to be 16 weeks for that, want to book it ASAP

I know I could just wait til next week and see what they say but it's hard! lol x

Thanks

 

[xprincessx]

Your due date will be calculated from the first NHS dating scan you go to, they will disregard your private early scan even though the earlier you get a scan the more accurate it will be.

 

[tallybee]

Thanks hun, this is what I kind of thought, will have to wait and see what they say next week xx

 

[Mrs G]

The 12 wk scan does seem to be law! They changed dad's due date at my 12 wk scan even though I knew exactly when she was conceived cod we had ivf!! Xx

 

[His Princess]

Same as Mrs G. We were 100% sure of our conception date since we had IVF but the EDD was changed twice. My original EDD was 27th July. At my 7 week viability scan, it was brought forward to the 26th, and at my 12 week scan, they brought it forward again, to 23rd July.

It's all done on measurements but after the 12 week scan, they won't change it again. As annoying as it is, I'd wait until after your dating scan to book your private gender scan as they won't do it before 16 weeks x

 

[tallybee]

Thanks girls xx

I know I'm just being impatient lol xx