Dating

[BeeYouTiful]

I bet a million people have asked this before, so I'll make you all roll your eyes and ask again

The first date of my last period was 1.12.18 which would make me around 6w4d.

However, in reality I know I DTD on 16.12.18 only! So two weeks after the first day of my last period.

Essentially, how will this altar my dates? I feel like I'm kidding myself saying I'm 6 weeks 4 days when in reality aren't I obviously less? As I wasn't no where near pregnant the first two weeks of the month?

I understand the first two weeks that you're pregnant you aren't actually pregnant, so surely i'm 6 weeks 4 days minus however long it took for the egg to fertilise?

I'm sorry for the head blag 😃

The dates are calculated from the first day of your last period, and then however many, 268? (280 something?) I think, days added to that to give a due date. An egg only lasts for about 24 hrs and yes even though its 6w4d, the first two weeks you hadnt ovulated nor conceived. Just the way it is worked out. They base this on a 28 day cycle with ovulation at day 14, if you ovulate earlier or later then the date will be slightly out but they have no way of accurately taking that into account. for example I am 18w3d by last menstrual period, due date 15.06 - I know I ovulated day 16 so its actually 17th for my due date. Then add the dating scan at 12w which says I am now 19w2d (which is near impossible given I was tracking dtd and ovulation/period) rather than 18w3d. - the dating scan is the date they will go by once you have it. Then have the 20w (or 19w in my case) and it changes again!

Confusing I know! and all that above probably hasnt helped!

in answer to your actual question (sorry if i confused you with prev post!), you are still 6w4d, and they will go by that for booking you in and doing the ultrasound dating scan - at the scan they will measure the fetus and plot it on a graph to determine how far along you are.

It won't alter your dates. You're 6w4d. The embryo is obviously two weeks younger than that but the standard measurements at the scan are labelled to correspond with measuring the pregnancy from last menstrual period. I.e. at 12 week scan, 12 weeks since last period, the baby measures "12 weeks". Obviously in reality you don't get the scan bang on 12 weeks, and the baby can measure big or small, but those two weeks are fully accounted for in scanning/pregnancy science.

Honestly, don't worry/think about it!

You are 6w4d, it's just how they date it. I know it seems odd.

Pregnancies are basically dated from 2 weeks before conception if you ovulate on day 14. In other words noone is actually pregnant until week 3-4 of their pregnancy. So if you had sex on day 16, you might find your due date is pushed back 2-4 days when they do the dating scan, but not by 2 weeks, because thats just where they measure from.