Incorrect Due Date?

[AlexPea]

Hi Mumsnet,

First post here 🤗

I had my 12 week scan yesterday which was amazing, and thankfully tests all came back normal.

However, the doctor put me at 13+2 which felt a little further than expected so she measured again to be sure. After the appt I did the maths and that puts my conception date at 10/11, however I started my last period on 16/11. This makes no sense right?

I'll call the hosp on Monday to query it, as I want to ensure I have an accurate due date (don't want them to start suggesting inducing too early!), but also - does it mean I probably have a huge baby?!

Has anyone else had experience with this? Thanks :)

You may have ovulated late.

Your EDD will go by the measurements of the baby from the scan - that's the date your MW will stick with. Doesn't mean you'll have a huge baby.

My due date was changed at the scan with my first. I did explain and they said no it goes by scan dates they are accurate.
Got to the end of pregnancy and I was under great pressure to be induced only because I was past my due date. Was told I had to go to the hospital and speak to the midwife in charge of the labour ward and a doctor. They told me how scary the midwife in charge was.
Got there they put me on the monitor, they said I was already in early labour which I knew, midwife in charge was fine and said that baby will be out soon. doctor sat down for a chat. Asked me when my period was, are they regular, got her wheel out recalculated my due date and said you’re fine for another week. The scan at 12 weeks can be a week out either way! Baby arrived 3 days later by emcs after labour actually got going.

I had this too with my now 3yo. I knew the date I dtd that lead to conception... Dh works away and he managed to get back for one night when I told him I started to get ewcm, so was only that one time... Anyways I knew when I found out I was actually pregnant that I conceived either that same night or realistically with a few short days. I had a few concerns so was scanned multiple times up to the 12wk scan up til around 9 weeks they put me behind then at 9wk+3 I was scanned and given that same gestation. Staff told me that the earlier you are its easier for it not to be as accurate but as you got closer to 12 weeks it's more accurate. Anyways based on that scan of 9+3 I had official 12 scan booked for when I was 12+2. When I turned up I was jumped forward to 13+4 I knew I couldn't have conceived as DH was away I knew I was actually only 12+2 but they put down 13+4.
So I went from being behind my dates to bang on to Infront of my dates.

We have concerns at end of pregnancy and (new) consultant wanted me to be induced as soon as I reached 37weeks, I mentioned about the week out and he was fairly dismissive of me, like he trusted his colleagues scan date over me, gave me the choice but as I was scared for baby and reassured if my dates are wrong it'll be better all round for baby to be born at that time I went for it.
Baby was a tiny 5lb and very jaundiced. Midwifes after birth then agreed she seemed like a 36 weeker over 37 but didn't make much difference long term.

My only thing to point out as it's same time of year as me.. my due date was very end of September/begij October (based on dtd) but due to 36weeks induction she was born 31august meaning I have to fight to have her start school as if she was born in September. Since it means she falls into the year ahead and as medical records show born at 37 I don't have a record of her being perm. I don't want her to start school when she would technically still be 3 if it wasn't for the issues we had at the end.

Anyways that was a long reply and I'm sure you won't have any troubles and need delivery brought forward but wanted to let you know.

That's really helpful, thank you all!

The other thing I didn't mention was that I couldn't have conceived on their estimated date as I was working on a big event doing 18hr days and definitely wasn't going home and shagging that week 😂

I'll speak to the hosp now and hopefully avoid a battle further down the line when I have other things to deal with (such as a massive baby 🙃).

Thanks again ladies xx

I measured a week ahead at the 12 week scan, which would have meant that I conceived a week before we even DTD, I went overdue and had her on what I believe the due date should have been, she weighed 7lbs 10, so measuring bigger at the dating scan doesn't necessarily mean you'll have a big baby :)

That's good to know thank you - worrying about my poor vagina already 😂

Don't know if you're already aware, but how pregnancies are dated does tend to be a bit confusing (basically you are still counted as pregnant from the first day of your period, and probably didn't ovulate and conceive until around 2 weeks after that). It's NOT dated from when you DTD and conceived. It also depends on how long your cycle is. If your last LMP was 16/11 and you had a 28 day cycle you would be 13 weeks right now.

@AlexPea its normal they go of the size of the baby, mine always measure ahead, currently 2 weeks ahead at 29+1 so will be having him early!

They won't change the date. I'm in my third IVF pregnancy, so absolutely no doubt about the exact hour of conception and they still go by scan measurements at the dating scan, not time of conception.

They will go off measurements and the reason why they use the 12 week scan to give a due date is because that's the most accurate dating, babies size will mostly stay in line with period dates but babies grow at different rates! Unless there's a major issue you can refuse any induction, so if you wanted to wait closer to 38/39 weeks you can make that choice, also you may find baby with level out in growth later on!