Due date calculation

[am398]

Hi, just wondering if anyone can help me calculate my due date. For starter I have no regular periods or regular ovulation, so of course this confuses me as every due date is calculated from the first day of your last period. I found out I was pregnant with a very light line on a test on 25th October I tested again 1st November test is dark and readable. Do you add 2 weeks at the start as conception or could I be any amount of weeks along? And also how soon would a early test show along as positive for someone like me?
Thanks. I am so confused😬! I better add in also that I have guessed about 5 weeks as I've calculated from weeks of how dark tests work + 2 weeks conception!

Due date from LMP is just a very early guide based on a very average cycle with ovulation right in the middle of the cycle. It's a starting point so midwives can book your appointments and scans in but it's not accurate for a lot of women (myself included). Just be honest with the midwife that you don't know.

Once you have a scan, actual measurements are used to give you a more accurate due date - I knew my LMP date but I have long, irregular cycles and knew I ovulated late, my actual gestation from the scans is 10 days less than what I would be going off LMP.

If you know when you conceived, then yes, add 2 weeks on for an approx gestation.

In your shoes if I was trying to have an early guess, I'd say I got the light line at 10dpo which would make ovulation around the 15th Oct, then add the 2 weeks to take you to 1st Oct.
Add 40 weeks so due date would be around 8th July - very approximate but that would be my starting point

Dates from LMP are not 2 weeks from when line shows - that's a rough date for conception. It's a further two weeks before that.

BTW, when did you actually last have a period, and what is the range of interval between them? MWs ask this, as they use this info (somehow!) to help in working out your rough EDD (I don't see how it adds to the test info you have though)

So with a strong test on 1 November, that gives an estimated (as if regular) LMP of 4 October, and EDD of 11 July (v similar to what PP said)

Your EDD will be recalibrated at your 12 week scan - which you should have c.27 December based on those EDDs

I don't get it at all there is not much info for women who don't have regular menstruation. My last bleeding was from august 27th- September 25th. Unfortunately my hospital don't give you your fist scan until you are between 20 and 22 weeks, it's a very long wait until then.

Thank you! It's so hard to judge I just want to have a good guide, I have a feeling I ovulated early, my estimation was July 8th also! I think I'll stick with that and go private and get an early scan done in the next few weeks to confirm!

If you're not sure when you ovulated or when your LMP was, then I'd work back about 4 weeks from the date of your faint positive test and use that as the date of your LMP. I'd say that's about as accurate as you're likely to get before your dating scan.

All you can do is base it off your last period which at least means you won’t be waiting as long for your scan because you won’t be as far along by 20 weeks based on LMP.

Personally I would gauge that you were approximately four weeks pregnant when you first got the positive and use 27th September as a realistic date for what would have been your LMP if you had regular 28 day cycles.