Help with due date please!! (Sorry technical and long)

[Ericam]

Am about 20 weeks pregnant. Baby conceived naturally on 26th Feb (I absolutely know this unless having secret life that I am unaware of!).Scan on 28/3/08 they said I was 6 weeks plus 6 days. Scan on 02/05/08 they said I was 12 weeks plus 6 days (ie. effectively added a week). According to my date of conception my due date should be 18/11 but hosp are insisting on 8/11. Have another scan this Friday 4th and really want them to change the due date back as had c-section last time and would like to avoid one this time if at all possible. So important that they don't start twittering too early about me going overdue as won't induce with previous c-section. (LMP 7th Feb - not good about cycle length as had been having IVF, then on and off pill (long and boring story!) But think usually about 30/31 days.) Only other vague possiblity is conception 3rd Feb but had period after that and that would make me effectively 24 weeks pregnant which is ludicrously unlikely. Any thoughts? Has anyone else had this problem?? Very grateful!

I had something a bit similar in that the first scan showed a later conception date than subsequent ones. I did some research and it seems that the earlier the scan the more accurate the dd estimate.

iirc it was something like in the first trimester it's accurate to +- 6 days, by the third trimester it's +- 3 weeks!

So go with your earlier one. If necessary, I would lie about your lmp.

When I was pregnant with DD my scan date and the date I knew I had conceived were out by 8 days. The midwife told me she would always go by my dates and told me to manually alter all the dates in my notes to avoid early induction. Have you told your widwife that you are 100% sure of your dates (don't tell her 99% because that will plant doubt in her mind)? Have you asked to be treated according to your own dates? I bet they would agree if you insisted.

Thanks all! Really helpful. Same for me re: DH being abroad (and I wouldn't have forgotten as we had JUST moved to Italy and DH went skiing for 2 weeks to the US 5 days after we arrived leaving me to settle DS (4) into new Italian school with neither of us speaking Italian... another story really but maybe if I tell the midwife she will know quite how sure I am as it is scarred on my mind for ever!!). Funny moment at 12 week scan when the ob suddenly saw the look on my husband's face as he inisted that "this baby must have been conceived at least a week earlier than you say" then after going on for about 5 minutes obviously realised potential embarrassment and said "oh well we can talk about this later". Anyway will simply insist - in the end it's up to me eh?

Hi ericam, this is pretty much the same for me. I didn't get my first scan til around 19 weeks, when I was given EDD of 20 June - and an impossible conception date, as I was in a different country to DP!

My LMP gives me a date of 27 June, and if I work it out from conception date - like you, I am 100% certain of the date! - it would be 25 June (so I'm over now whatever date I pick!).

At my booking in appointment, the mw asked which date I wanted - I chose the 20th - mostly because of work issues/mat leave - and also to give myself the option of 'early' induction if things were getting too much. So they weren't too bothered about the date at that point I think.

Anyway, my notes still say the 20th, and have had a few mws telling me that I would be booked for induction by the 30th (today), but I've stuck to my guns - had a good chat with doc last week, and am going to see them again tomorrow.

Don't forget you can refuse any treatment, and ask for monitoring and expectant management, which is what I'm going to do (and I'm having my first sweep tomorrow). If there's any risk at all, I'll go for induction, but I'm not going to be scared into it if my baby just needs a little more time to get himself ready!

As Starlight says, conception date could be slightly different, as egg and sperm can both hang around - but it wouldn't make your date any earlier, it could only be later.

Good luck!

Thanks whinegums. Hope we hear some good news from you soon!