Due date

4 replies

okeydonkey · 04/02/2015 22:25

This probably comes up a lot, but I got pregnant and it was a surprise.
My Last period date gave me the due date of 12th March. But my 12 week scan date gave me 1st march as the due date.
As it's getting closer I'm thinking I should go with the 12th March as I don't want to wait and wait but if I have a later date in mind I won't feel like I'm waiting.
What's more accurate the period due date or the 12 weeks scan date?

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misseskimo · 04/02/2015 23:30

I know with scans they measure based on size, whereas NHS calculations are based on a standard 28day cycle, and working from AF and avg cycle dates are generally more accurate due to being tailored to your own cycles. However not all cycles have a standard 14 day lunar cycle and so if you ovulated earlier/later than usual on that particular month, even though your cycle remained the same length, it would still affect your EDD.

Also as scans are done on baby size compared to the average size for X weeks, if baby has had a growth spurt that could change again later on...

With mine, by NHS calculations they put me at 11/07, but by my calculations it was 15/07... I had 3 scans at EPU at 6, 8 & 11wks, the first two they said my calculations were right not NHS, but at my 11wk they put me forward a whole week to 07/07... This was then confirmed at my official scan at 13wks as being my new due date. I'm half expecting that to change at my 20wk in two weeks time!

Either way, baby will come when it wants to! I was due Christmas Day and arrived 7wks early with no medical reason other than just early! Whereas my friend got to 42wks recently before they had to induce her. So no telling really!

Good luck though, not long left now! X

Original poster

okeydonkey · 04/02/2015 23:47

Thank you.
No not long. It hadn't bothered me up to now. I think it's because being this pregnant you want an accurate date to work with, but I suppose they aren't accurate like you say 7 weeks early or even 2 weeks late.
I think I'll work towards 12th March. I'll chat to MW at next appointment too.
I'm convinced it's due 12th March as there was only a handful of time conception could have happened which therefore points to mid March

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sleepybee · 05/02/2015 03:56

I think if you are under nhs care they don't change your due date from your dating scan usually done around 12 weeks even if at the anomaly scan around 20 weeks if baby measures say 2 weeks behind or 3 weeks ahead they won't change your due date. At 24 weeks my bump measures a week ahead but at 28 weeks it's exactly as it should be for 28 weeks so shows that your baby may just grow at different rate but should all catch up at the end.

bwow · 05/02/2015 07:05

Under the Nhs my midwife calculated my edd going from my last period. I had an early scan at 8 weeks which said I was further along than thought. It happened again at my 12 week scan. My due date is now 6 days closer than originally planned. You can see in my notes where it has been scribbled out. I'm the same, im convinced I will go over as the new dates don't seen to add up! Only time will tell.

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