ultrasound vs GP dates

[pelaja]

I had my 7 week scan today and all appears normal. Baby's heart beat was 136 bpm. The ultrasound person told me I'm only 6 weeks pregnant but my GP says 7. I'd prefer to be 7 because there's less weeks until the end of the first trimester. I don't understand if you take the date of your last period and count each week after that it works out 7.

has this happened to anyone else?

thanks,

[kirsty]

You are still only very early on & maybe bubs was a little hard to measure? You may find that if you have another scan at around the 12wk mark you may get a different date.

In my case I have said from the start that my EDD is August 10th, but my GP says August 12th, the ultrasound said August 14th & the OB says August 10th. So a few different dates there, when the OB discussed dates & the fact that the ultrasound was 4 days later she said it wasn't a big deal as it just basically confirmed when my last period was.

[brodes80]

I had similar dating probs. My GP dates &US dates were 3 weeks apart! Also the sac was the size of 10 wks & bub 8 wks (he had a big sac)!! turned out i "superovulated"- 3 days before period due - the u/s was the most accurate. Bubs was born exact date predicted by u/s.

[peony]

Hi.
Im new to this board but have been lurking for a while
I thought i was 8w3d at my scan last week but was told i was 7w1d. (due to egg dropping late!!!)
Very disappointing....but everything was fine, he reassurred me.
But just wondering as well.....which week do i count?
(Basically trying to count down until this horrible morning sickness stops).
Best
D

[kyliealysha]

I just asked my OB about this, because two separate u/s have told me different things. He said the first one (I thought I was 6w3d but according to the u/s I was 5w4d) is the most accurate. He told me that the early ones are more accurate because at that stage all babies grow at about the same rate. By 12 weeks (my 2nd u/s) babies have started to grow at different rates depending on how much the mother eats/how much exercise she does etc. SO I guess I am a week further back than I thought

[Fee]

Counting from my LMP my due date was 15 July.

But when I had my first scan the baby measured 6 days earlier giving me a due date of 21 July. So my dates went backwards! The OB keeps both dates on his records but we (myself and the OB/midwife) go by the scan measurements which means I'm 16w today instead of being 16w6d.

It sucked going backwards a bit! But nevermind. You forget about it after a while!

It's all just an estimate anyway. The baby could come 2 weeks either side of the date.

[Fee]

I thought i was 8w3d at my scan last week but was told i was 7w1d. (due to egg dropping late!!!)
Very disappointing....but everything was fine, he reassurred me.
But just wondering as well.....which week do i count?

I would go by the u/s date (the measurement of the baby). That's the one the OB will use anyway so you might as well use it.

The whole counting from the LMP only works properly if you have a "regular" 28 day cycle. When I showed my OB my FF chart he said my new dates made sense with the length of my cycle and when I O-ed etc.

[peony]

Thanks for the info Fee.

What a pity though, going backwards...anyway, I'm sure i will forget about it if I get further along.
best
D

[Alan]

Hi pelaja

Your first U/S is the nost accurate way of finding your EDC. However this date can be out by a week either way.