Scan dates say im 12 weeks and 2 days pregnant but i couldn't of conceived until 11 weeks and 2 days ago is the scan based on your last period or did you conceive 12 weeks and 2 days ago?
Your hunch is right; the ultrasound date is based on the day your last period ended. So, on average, the 40 week pregnancy begins two weeks before conception has even occured.
