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Pregnancy

Talk about every stage of pregnancy, from early symptoms to preparing for birth.

Original poster

Due date: 12 week scan or last period?

15 replies

MissMarion · 01/04/2021 18:04

Hello ladies...

So this might be a stupid question...

At my 12 week scan they moved up my due date by 5 days compared to the date estimated from my last period as baby seemed to be 5 days ahead of schedule. It’s a bit weird as I know exactly when my last period was and when I ovulated (as I was tracking), but anyhow.

My question is, if this happened to you, did you adjust how far along you were based on the new due date, or did you keep counting from the date of your last period?

Thanks xx

OP posts:
BumpLoading · 01/04/2021 18:06

Congratulations on your pregnancy!
I use the due date given by the scan, my baby came closer to that date than the one from my last period too.

RaspberryBubblegum · 01/04/2021 18:11

I counted from the date they gave me even though I know they must be wrong (as it would mean we conceived before we had sex). But babies are rarely born on their due date anyway so it doesn't really matter they way I saw it. My two were 8 and 12 days overdue so were late according to my last period too 🙈 congratulations! 💐

Muriel84 · 01/04/2021 18:13

Hello! I had this and I was fairly sure the date I conceived even though I miscarried the cycle before (at 5 weeks so very early) as was tracking ovulation etc. I was moved forward 5 days. You don’t have much choice other than to accept the date from the scan and apparently the dating scans are a lot more reliable than your last period for various reasons such as you may have ovulated earlier than you think or implanted quickly. I found it a bit tedious as I officially went 11 days over so all felt very drawn out. It was hard not to fixate on dates etc with such a prolonged waiting game at the end! Good luck x x

FeistySheep · 01/04/2021 18:25

It's easier just to go with their date as it'll be on your notes etc. I think you can fight them to change it if you want, but why bother? Just bear it in mind at the end - if they think you're five days further on than you actually are then they might start pressuring you to induce at 41+2 rather than 42 weeks. Stand firm if you're positive you know when you ovulated.

SnooperTrooper12345 · 01/04/2021 18:27

I went with the date they gave me.
They put me back 4 days.
Easier anyway because everything will be using this date so no point using the date you think.

Poppiesway1 · 01/04/2021 18:34

Ultrasound dating is not exact and can be 5 days out either side. However the date they gave you will be used to assess growth at later scans and your tummy measurements.

LauEli · 01/04/2021 21:12

I had this at my scan, put 6 days forward so sil just go with their date and see how it pans out. First baby was 10 days early so it's not an exact science

Worriesome · 01/04/2021 21:32

At my 12 week scan my due date went back by 4 days. I’m going with that, but like people have said it’s rarely bang on with a due date, it’s just an estimated date and baby can come before or after x

SaveWaterDrinkGin · 01/04/2021 21:36

The estimated due date given to you at your scan is based on foetal measurements and is the date that will be used throughout your antenatal care so you might as well forget the other date completely.

Congratulations.

MintGreenLife · 01/04/2021 21:48

I knew for certain when I ovulated too as was charting BBT and using OPKs. I had irregular cycles since stopping the pill, so I was about two weeks less along than from LMP. A scan at 7 weeks put me spot on for ovulation date, but at 12 week scan baby had gotten ahead by 5 days. Your official due date is calculated from your 12 week scan, so from then I’ve just stuck with that. It’s the date the NHS/midwives etc will go ok, so just made sense for me to work to that date also x

MintGreenLife · 01/04/2021 21:49

Also I’ve had my 20 week scan now too, and baby is still measuring right for due date x

bluebluezoo · 01/04/2021 21:52

Makes no difference. Other countries use due date +/- 2 weeks, so effectively a 4 week “due date”

Chances are the baby won’t come on that day, it’s just a marker to calculate risk of baby coming too early or too late.

My hospital doesn’t move due dates unless they’re more than two weeks out. No point.

Chelyanne · 01/04/2021 22:05

Our baby measured 4 days ahead of lmp at the dating scan, I go with that due date to calculate how many weeks I am. She was measuring perfect for dates at her anomaly scan this week so it confirms the dates.

Our eldest was different. They moved dates forward 10 days at dating scan but at anomaly she measured 9 days behind. They still kept the same due date and she was born at 39+6 weighing an average 7lb 7oz. She was smaller than our twins who were born at 38wk, our other singletons were huge compared to her.

PFin · 02/04/2021 00:45

Id go by due date given by hospital! This is going to be the date recored in your notes and used by all the health care professionals involved in your pregnancy so its best to stick by this date. Its strange they changed it tho, I had a scan and the sonographer said they only change the due date if its more than 11 days out. This must just be my hospitals policy tho! Good luck OP 5 days in the long run is nothing!

Rtmhwales · 02/04/2021 00:54

I live abroad but doctors and midwives here just kind of give a broad three week range for your "due date". Babies are so fickle.

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