Tinkerbell, it is confusing. It is different in different parts of the world and even at different doctors.

Did she give you a due date? It is easier to work with a due date based on the scan. From the numbers you gave it looks like she used the Menstrual Gestational Age. Did you have cycles around 32/33 days?

i actually went for a termination appointment so she only gave me a quick scan, she didnt say my due date. i have changed my mind now though and i want to keep the baby. the midwife said they date it differently to the one the lady at the hospital scan gave me, the midwife said my due date would be the 24th of may 2010 but she said she goes off the first day of my last period. when i spoke to the nurse at the hospital today she told me they do not add 2 weeks onto the scan date, but the thing i dont understand is if the scan dated me as 8 weeks and 3 days why did she say i concieved between the 27th of august and the 3rd of september? do you know what i mean? lol i am so confused coz then that would only make me 6 weeks and something, althought she did say it could be up to a week out, but no longer than a week. would it have been possible to concieve on the 5th or 6th of september? i dont think it would have because the scan wouldnt have shown up as that much would it? thank you very much for your help by the way

The nurse is probably technically correct. They do not add 2 weeks. It is already built into the tables and equipment they use. Automatically.

You normally ovulate 14 days before your next period. Unprotected sex from about 3 days before your ovulation is your most fertile time. From 5 days before ovulation it is still quite possible and 7 days before is the outside limit.

With 28 day cycles ovulation would have been around Aug 31. So unprotected sex from August 26 to September 1 would be the most likely baby making sex.

From the scan data your ovulation was Sept 4 so sex between August 30 to Sept 5 would have done it. The scan is normally very accurate at 8 weeks. (This would mean a cycle of around 32 days when you conceived.)

Best of luck!