Hi, quick question.. I have been dated from conception(gestation) 20/11 (by ultrasound and measurements) rather than my LMP 6/11, so my EDD is 27/8 rather than 13/8.. is this right and will I be allowed to go overdue as the 27/8 falls 42 weeks from my LMP.. aparently dating from lmp is 'the old fashioned way' according to a lady from the hospital? Concerned about being allowed to go overdue by 2 weeks and it be 44 weeks from lmp
Thank you in advance
The most accurate way to date a pregnancy has been proven to be ultrasound at around 11-13 weeks of pregnancy so this is the date that everyone involved in your pregnancy will go by.
Agree with that.
With my three pregnancies I was first given an EDD based immer LMP and then at the ‘12 week scan’ was given a fixed EDD.
My son was given a 3 day later EDD, my daughter was one week later and my last one was 5 days earlier.
With the last I was most confused as I had a scan when I was ovulating so we absolutely know when I was ovulating so adding two weeks to that would’ve give us a due date for the 14th april and then 9th April. He was induced on the 1st April and was 9lb, so I’d agree that going by the 12 week scan seems more realistic. Imagine he’d have stayed in for another 2 weeks!
2 weeks difference seems a lot though, I have to agree with that. I would say just bear in mind your original due date and see how things are in your third trimester. If you are, for example, measuring very very big then I’d bring up the fact that your original due date was 2 weeks earlier. They should give you extra scans for measuring big either way!
How frustrating it must be for you to have gone through two extra weeks only to be Taken back by two!
I pushed to be dated from conception (I knew when I ovulated due to the pain i’d experience at that point in my cycle) rather than lmp as I didn’t want doctors to be fixed on effectively inducing me 2 weeks early when the time comes; especially as an older mum.
As it turns out the EDD, based on scans/measurements, was only a day out from the date i’d worked out based on conception date.
Don’t worry, just go with whatever date you get from the scan
Okay perfect, so when you worked it out was your edd 38 or 40 weeks from conception?
It was 40 weeks from conception. IMO that’s more accurate as we tend to ovulate a few weeks after our period (in fact I was a little longer than that in my cycle as everyone varies a bit)...the time between LMP and conception isn’t relevant to baby’s development as they don’t exist yet.
I also used this before I had my scan (it’s meant to be one of the most accurate calculators for due date available) and it gave a date within 2 days of that given after my dating scan: babymed.com/pregnancy-due-d...
In short, provided there are no other concerns with your pregnancy, you shouldn’t encounter any problems with being able to go overdue by 2 weeks from the EDD you’ve been given, which is from conception date/measurements rather than LMP, right? If that’s the date now in your notes that’s the date the doctors and midwives will now work from.
Is there a particular reason you’re worrying about it? As you seem quite concerned.
Okay I'm with you.. so it is still safe to go over by 2 weeks which would fall 44 weeks from my LMP? Everything seems fine up to date, I have been very lucky to have not had any complications or problems as of yet.. I have just been very concerned that it wont be safe for me to go that far past my LMP as with my first, they got my dates wrong with her being such a tiny baby and she came out practically dry where I was allowed to go so overdue.. My second, i cant for the life of me remember how they dated me! I just want to be sure it's going to be safe and I am not going to encounter any complications due to being so past LMP even when the first 2 weeks (between 6/11 and 20/11) as you said, I wasn't pregnant.. as long as this is actually how they date pregnancy now and i (finally) understand, i am happy!
Thank you for all of your advice everyone
Also with that calculator and every calculator I have managed to find on the net, it is dating me 13/8 not 27/8.. 40 weeks from LMP not conception.. I pretty much have a perfect 28 day cycle so every calculator has told me the same and even when I type in my 'conception date' as per scan and which actually falls exactly 14 days from my LMP, it all comes back to 13/8 not my given EDD 27/8.. I think maybe they are not working for me in this situation and have just helped confuse me that little more😅🙈 I think they have maybe not updated them since the 'change' of the dating procedure, just all so confusing!
That is strange how that’s working. I had a variation of about 4/5 days for the EDD based on whether I entered my lmp or ovulation date.
Although your cycle is 28 days it doesn’t 100% mean you ovulated at exactly 14 days I suppose (mine was 35 day cycle and ovulation day varied).
It will be interesting to see when baby turns up 😂 Just keep pushing to be monitored if you have any worries. Good luck
With my first I knew the date I ovulated and the ultrasound measured and predicted exactly the same day as the pregnancy calendar.
Now with my second pregnancy - I had no clue when I ovulated/conceived but based on my LMP I should expect baby on 28th August. But based on the ultrasound babys Due date should be 8 days earlier (meaning that I conceived the day after my period ended.)
I understand your worry. Specially as there are 2 week difference.
Hopefully your baby will ripen up well and will be born in a time slot that won't bring any anxiety!x
Thank you everyone! So it is correct to be dated from conception not my LMP? I have raised this multiple times with medical staff and no one seems to be giving me a clear answer which, yes, is VERY frustrating!
You’re possibly not getting an answer because it’s not really a ‘right or wrong’ scenario. TBH I’d forget about the LMP/conception date as while they use them as a reference point they’re still only really estimating the birth date even on the measurements at the scan...bear in mind 4% of babies are born on the EDD that’s been given.
As long as baby arrives between 37-40 weeks (42 max if you go over due and there’s no other concerns) that’s the preferred window for a healthy baby.
42 weeks from LMP or conception? As with my given due date and being exactly 32 weeks today instead of 34 (from LMP) if I go to 42 weeks, I will be 44 weeks from LMP.. I'm very concerned this isn't going to be safe..
The medical professionals will work off whatever EDD is recorded on your notes now. Unless there’s a sign baby is in distress try not to worry unnecessarily
Sorry, what's LMP? feel a bit silly for not knowing 😂
And my original EDD and the one derived from scan only differs by a day, so I was lucky lol x
Went for a scan today and the sonographer said that my 'gestation' date of 32 weeks on my notes doesn't actually measure back to conception?! He is the only one who has said this and I was sure that 'gestation' is the space pf time between conception and birth?! and the baby measures to 32 week measurements.. Starting to feel like no medical staff actually really know what they are talking about😅
so were you dates from your last period or contraception? 
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