Ist timer needs help with dates !

[Rosem1]

Ok I?m now a little confused so bare with me. The date of my last period was 4th of March 2010 and I have a good idea when I ovulated on that cycle so when I calculated the date of may last period and cycle length (36 days on this cycle) I got a predicted due date of the 17th Dec 2010. Fair enough. I had a dating scan on Tues this week so in theory that day I would have been 11 weeks and 5 days pregnant but she measured the baby and it says on the paper work 10 weeks 3 days with a due date of 18th Dec 2010. I understand that going off the day of your last period is slightly false as your counting pior to Conception but I thought this is generally how its measured not from date of conception. So now I?m not sure how pregnant I am officially speaking !!!

Hope this make sense 

you should go from the date from the scan, so you're 10w3d especially with variable cycles as it sounds like you have.
Sorry you'll have to do that week again in pg terms!
same thing happened to me too - I must have ovulated late.
congratulations!

I'm assuming that you ovulated over a week late from what you know? Which would fit in with the new EDD being similar to what you calculated using your cycle length.

How pregnant you are is based from your LMP, but this assumes you ovulate on cycle day 14 and many women don't, so the dating scan can change your EDD. But they still include the theoretical 2 weeks pre-conception.

So you're 10+6 today.