QUESTION ABOUT ULTRASOUND. Keep getting told different info😤

[MamaD6]

does an ultrasound measure your baby's measurements from conception e.g if your babys measurements measure 10weeks +5, you can count 10weeks +5 back from that date of the scan and that works out when they were conceived?

And the doctors, NOT the ultrasound machine, adds on 2 weeks that you are not pregnant or does the ultrasound machine add 2 weeks you were not pregnant from your LMP?

[ChrisWest1983]

All my scans calculated my baby's Due Date regardless of LMP.

I know- very confusing...

With my first I knew exact conception day/ovulation day. The scan showed consistently the due date that was 1 day before my calculations of my DD (on NHS website)- including the 2 weeks when I was not pregnant , as I ovulated exactly on day 14th.

Now with second I never knew when I was ovulating. After LMP the DD should be on 28th August (if my ovulation would have occured on day 14th).

On 12w scan (which apparently says the most accurate date after measuring fetus) it states my DD is on 20th August, so doctor moved my DD to this 20th August, 8 days ahead. But 30 week scan predicted DD on 13th August 🤷 go figure...

But yeah - scans don't care about your LMP.

Not sure my answer helped you, but if you got confused - ask more questions and I'll try to explain it differently.

Best luck!

[ChrisWest1983 in reply to ChrisWest1983]

As they moved the DD it means I should have ovulated and conceived next day after my period finished...

The second predicted date means I got pregnant just before my period... I am confused too...

So - I am expecting my baby sometime from mid August to end of August .. 🙈

[ChrisWest1983 in reply to ChrisWest1983]

So - as you see : the Ultrasound does not exactly determine when you conceived... Same as it does not tell you the exact babys weight... My boy was predicted on 50th percentile but was born on 9th. They measure head circumference and belly etc and calculate using an algorithm, but my boy was very very skinny - no fat on arms and legs - so he was only 6lb1oz...

So I don't exactly believe the Ultrasound results about the dates and measurements, but I rely on it as a great way of checking baby's organs etc.

[roxannacar]

Ultrasound and doctors use the lmp (so add two weeks before conception)

However they are only indications and not 100% accurate and babies are considered full term from 37 to 42 weeks so pretty big variety.

My point is the dates make little difference as baby comes when they come however if theres a paternity query the only way to know is a DNA test