Estimating due date after coming off the pill

[Yavannah]

I am 9 weeks (we think) pregnant and 3 weeks away from a dating scan. I like to plan and I still keep wondering if I might be further along. The trouble is I only came off the pill (after 12 years) at the end of February, I had what I would class as a normal bleed on time for the end of my pill cycle. So I haven't had a "normal" period since I was 16, so nothing to compare to. But, the one period I had after (at the end of march) was shorter and lighter than my bleeds when I was on the pill. That's the period we used to date the pregnant, but according to the NHS and Ovia my "missed period" which prompted me to take a test was at 3 weeks not 5, and I wondered if my period was actually implantation bleeding. If so I am 4 weeks more pregnant but with no way to tell. Saying that I had no pregnancy symptoms until my currently estimated 4th week, and it seems unlikely I would get zero symptoms until the 8th week. Is there anyone with experience of getting pregnant so soon after coming off the pill that has any idea if I am worrying over nothing?

Hi OP, no direct experience but maybe you could book a private scan? They could measure and tell you approx gestation.

It's absolutely possible to not have symptoms until 8 weeks! I was 7.5weeks when I discovered I was pregnant and had a little bit of nausea and nothing more. I hadn't had a period since my last miscarriage so didn't know how pregnant I was. I spoke to the epu who measured my HCG to determine when would be a good time to book an early scan. It came back very high so the scanned me the next day (a week after my positive test) and I was 8 and a half weeks! In a previous pregnancy I had nausea and vomiting at 4 weeks and that was equally unusual
What week is your dating scan for the two dates? It might be worth calling the scanning dept and say you are doubting the dates and if they could move your date earlier so that if you are more pregnant than you think they can still do the tests? Have you had your booking appointment yet?

My first appointment isn't until tomorrow and my scan is due for my 12th week, I did mention my concern when I was referred but I'm not convinced they could see me sooner as they seem to have had a lot of referrals!

I'd raise it with your midwife tomorrow and ask what the impact would be, I think the screening for trisomy conditions would be slightly different if you are actually more than 14 weeks but aside from that I don't think there isn't a huge difference but the midwife will be able to confirm. Whatever date you get at the dating scan will trump any estimated date from last menstural period
Had I not had an early scan my midwife would have used my miscarriage as my lmp and I potentially would have needed a second dating scan if I turned out to be too early to get the measurements they needed.

Hi, midwife here. Please don't waste your money on a private scan. The first scan pregnant women get on NHS is a "dating" scan. The sonographer will use a sophisticated technology and algorithm to work out the date of conception. Sometimes women who had IVF report a discrepancy of 1-2 days, I heard. It wouldn't be 1 or 2 weeks. I haven't worked in the community for a while. My recollection is the dating scan needs to happen at 11-14 weeks to be accurate. I hope it helps

I understand all that, but what is the impact if by the time I get a dating scan I'm actually at 16 weeks not 12?

Apologies, I really can't answer that question

https://www.nhs.uk/pregnancy/your-pregnancy-care/12-week-scan/

The NHS page on the dating scan explains that if you are over 14 weeks they use a different screening method for trisomy conditions

@Yavannah not knowing approx gestation would do my head in. I'd have to have a private scan soonish to put my mind at rest!

Thanks all, I will raise it with the midwife in person tomorrow, but if anyone does have experience dating the pregnancy after coming off the pill then please feel free to add it here :)

Theres no major impact. They just do the tests a little different.
My SIL didnt find out she was pregnant until 24 weeks she had other tests done instead as nuchal fold isnt tested later on, my nephew is 1 this month and is a happy healthy baby.

With mine, baby wouldnt sit right for the sonographer, so i couldnt have his nuchal fold measured. Im at the midwife today who will be looking at testing for all trisomys, if this hasnt already been tested for in my 12 week bloods.
I dont think you have to worry about being further along if you come off the pill, a lot of people dont ovulate straight away after coming off it.
If you have and you are 16 weeks there are ways around making sure baby is healthy.