Dating with 20wk US - need advice for something...

Ok, so I know dating at the 20wk scan is near enough impossible. But how badly out can they be? I assume its going to be affected by the overall size of the baby, so if I got told I was 23wks (due July 3rd) and I had estimated almost 2 weeks sooner (25wks) ... Is it possible to be that far out - or maybe even further?

I don't know my LMP (hate the rotten things. Don't find anything about the memorable) and there was only two dates for DTD to go by (bit iffy on them too) but being a girl it could have been a few days later...

Normally I wouldn't care - however I am going to QLD this weekend and I am wondering if I should throw the hospy bag in the car just in case. I actually don't mind either way so its not a case of finding someone to watch over me down here while DH is away - I know Logan hospy and had two bubs there already and thats fine - But I'd prefer having them glare at me for turning up in labour again (No one told me I had to book in with my first. Doc didn't even give me a referral - but this is the same tool who told me morning sickness is normal at 20-30-40 weeks) than have my DH do that drive alone.

Ugh - you found the question in there right? How far out are the notoriously incorrect dating at 20wk us. Would it be put out to way to far if this was say another 6lb baby? which is possible... My DHs family has 6lb girls and 8lb boys and so far he has not been the exception. Would Fundal height be a better judge?

Then again - my mums 6th with 12lb.. so maybe we are all miles out, LMAO.

our dating scan was 'spot on' according to the sonographer and with her arriving 2 weeks early it was pretty much correct with weights. But she told us that it is not unusual for there to be a 3-5 day difference...ITH...

hope this gives some light to your question...

Alright well, I can only speak from my experience but I never had a blood test or scan before 20wks so it was used as my dating scan. I was a bit lost on my dates as I was in Japan and then sort of put the pregnancy in the back of my mind. I was pretty sure she was conceived the day I returned or sometime during the week but had no clue when my last period was... anyway! My ~20wk scan gave me an estimated due date of 31st of March and my DD was born 2 weeks before that on the 17th, spontaneously at 6lb 9oz (2.9kg). I'd say it was pretty spot on, she acted like she was a little early but not too early... if that makes sense? If she was 40wks when born, that means she was conceived sometime before I went to Japan which is possible I suppose although (TMI) I did have light bleeding a couple of days of my trip but then could that have been implantation??... ah, who knows!!

Wow, this really wasn't helpful in the end! I am fairly sure that the dating scan was correct although I would love to think that DD has been to Japan haha. Who knows! If it was me, I would take your hospital bag just in case because you never know when babies are going to make their appearance no matter how accurate your dates are!

I don't know about the accuracy, but my 20 week scan this time around gave me an EDD of the 20th of August and the 12 week scan gave an EDD of the 21st. I think I'm due on the 22nd so it was pretty spot on for me.

The 20 week scan was pretty accurate with my first two pregnancies too.

I'd bring your labour bag just in case, it's better to be on the safe side!

I would take the bag, that way you are covered. My dating scans have all been fairly accurate, but they can never be 100%, so just give yourself peace of mind and take the bag :)

yeah, I was thinking that. Its a 'mercy dash' so I needed to minimise what I was packing and wanted to see if I could rule it out. I guess at the least I should have it because it has my birth intentions in it and mum wont know them where as DH knows the important stuff but might not be there if I went into labour (he has to go an additional 8 hours with dad and BIL).

Thanks!