How can I be a whole week more ahead than i thoughtin pgy?

[WinkyWinkola]

I know my lmp but at private scan, sonographer said I was 12 not 11 weeks pg according to the foetal measurements.My cycle ranges from 27-31 days but that's not a week's difference.

Both dh and I are over 6 feet tall. Would this affect the length of baby?

I don't get it.

I remember being in the same circumstances...

midwife said dont worry about it.. in terms of readiness to be born there isn't much difference between 39 and 40 weeks and when you get to 39 weeks you will be glad you dont have an extra week to go ..

I don't think that dating scans are that accurate. I know that we were given dates for dd that didn't fit (we knew very accurately when she was conceived). We are also quite tall (and dd has turned out to be too) so maybe that is a factor.

So nooks, when did your DD arrive then?

I'm not that bothered. Just intrigued. The sonographer had some pishposh kit and he was certain I was a week ahead

I had this with my DS said he was six days older than I thought and I knew exactly when I had conceived. He was a big baby and is still tall now. He arrived about a day before my predicted due date :)

She was conceived on Christmas morning (which is why I remember!) and I think my waters broke on the 4th September (she was eventually born on the 7th). It's funny I have always thought of her as being two weeks early, but I see it was three weeks, as that's only 37 weeks 'cooking'.

i wouldn't worry it may be that you have a long baby, the measurements are set in the machine and basically tells the sonographer how far along you are, if everything is ok you will go to 42 weeks so baby would only be brought early if there was a problem good luck with your pregnancy :)

They are not that accurate. One of the mums in my NCT group is IVF and so she knows the sonographer is definitely wrong. They insists calculating her due date from the measurements instead of her IVF date too.

Same happened with dd2. I knew date of conception as we only had sex once that month.

I didn't let it bother me too much as I was panicked about going two weeks over anyway. She was born at 40+13 by scan dates and 40+7 by my dates.

Maybe its got something about when you ovulated? I don't understand all this that much but I know that when you have sex it is not necessarily when you concieved? Something about sperm is able to survive for up to 5-7 days inside 'waiting for egg to be released? I don't know maybe just a thought..but then again if your tall that can affect the size, my sister for example is tall and her pertner and their son was measuring big all the way through pregnancy and now he is 3 and a half and is the size of a 7 year old! And then there's me, who's very short and having trouble getting shorts that don't look like 3 quarters for my DS!and current baby is measuring 3 weeks behind on legs!lol

But they don't do it from conception date do they? I'm only early but everything I see incl the GP does it from the date of last period, so the 40 weeks is the notional duration from period to birth rather than conception to birth. I'm no expert at all, but that is the only way it makes sense to me. Although it does then baffle me when they change the date, as they did after my scan but I guess that's it they're updating it with better info than the notional period.

This explains what I was waffling about I think www.babycentre.co.uk/pregnancy/fetaldevelopment/workouthowpregnant/

I know that conception is the real date to calculate from but I've done a reverse due date calculation online.

According to the sonographer's due date, I would have conceived during the days I had my period that month.

Now, i). I never have sex during my period. It's just my 'thing. and ii). We only had sex two times that month as dh was away a lot. On days 10 and 11 of my cycle.

So, could the sonographer be wrong and that my and dh's height is making the baby seem bigger?

Hi winky the same thing has happened to me. They have dated our baby 5 days ahead. I am sure of when I conceived as I used CBD OPK. I am nearly 6 ft tall and DH is over 6 ft tall. They expect embryos to grow at the same rate and therefore the size is consistent with an embryo at the day milestones.

I was scanned every 2 weeks in early pregnancy and at each scan until 10 weeks, they added an extra 2 days. At 10 weeks, they only added 1 day.

So, by actual dates, I'm 37 weeks today, but according to my dates from the 12 week scan which is how you go through the rest of pregnancy, I'm 37+5. Baby is in 95th percentile for size, (8 and a half pounds) based on average birth weights, and most of the size markers for him are at 42 weeks + at present.

Hope my explanation helps'

I know my due date is at least 9 days out, hospital says it doesn't matter and policy dictate that they ignore what the mother knows in favour of the scan. This means I fell pregnant just before/during my last period which is unusual to say the least ;)

I'll be reminding them of this fact if I get to be '9 days overdue' by their dates and they insist I HAVE to be induced. I know babies might come early but with three 42/43 week pregnancies, I can't see this baby spontaneously arriving earlier.

On the bright side as I am behind their dates, it does mean I should not measure to far ahead in this pregnancy. Yeah.

I got put forward by almost 2 weeks!! I know when I got pregnant down to the hour because I had only had sex once that month and was using ovulation tests.

Obviously hospital were adamant I must be wrong and their dates were correct. Yeah, I must be such an idiot to not realise having sex when I know I didn't.

Had had a growth scan and was told DS would be between 8 1/2lb to over 9lbs, was induced at just over "38 weeks", by my dates I would have been 36+5 and funnily enough DS only weighed 6lbs1oz.

I've been wondering about this too

Had my 12 week scan last month and the gestational age by ultrasound was a whole week ahead of my dates so according to them I was actually 13 weeks - except the thing I don't understand is that the length of the baby was measuring just below average for a 13 week foetus, I just don't understand that at all! Does anyone know why that might be? Are the organs developing quicker than the length or something?

Sorry to muscle in on your thread!

Now I'm really flummoxed. Just been for another scan and they say I'm 15 weeks 3 days instead of 14 weeks 2 days the private scan said or the 13 weeks 2 days that I thought I was.

That's two whole weeks out. Weird.

And I'm barely showing. Weirdest pgy.

Scans are extremely inaccurate for dating esp after 8 weeks. No-one HAS to do anything- if we know our dates we should stick to them or risk colluding with a system that routinely induces premature babies ( increasing morbidity for mother and baby with all associated risks of the epidural/ caesarean/ instrumental delivery that often follow)

ALLOW is not a word that should be addressed to a competent adult

Seriously? Scans aren't accurate?

Ultrasound dating has an 8% margin of error at 8 weeks' (or 56 days') gestation calculates to ± 5 days; at 18 weeks' (126 days') gestation, this represents a range of ± 10.08 days; lastly, at 28 weeks' (196 days') gestation, the margin of error continues to widen to ± 15.68 days.

This is because genetic factors come into play to determine how baby develops and that increases with gestational age.
So if you think of a margin of ± 5 days at just 8 weeks then when most of us are dated at 12ish weeks it is more like a week out. Hence ESTIMATED due date.

Which is why induction policy should be relooked at. If you know your dates then stick to them

(ref: www.medscape.com/viewarticle/703501_3 )

Babies develop at different rates before they're born the same as they do after. The measurements they use for dating are averages for that age gestation. I had 2 scans before 12 weeks and both were exactly right for days and weeks. I know when I conceived. I have a scan tomorrow and should be 13 weeks exactly in measurements but I'll bet you I'm not!