Ultrasound and Conception Dates

Jane Foley's picture

QUESTION

Dear Ms. Ultrasound,
I have had two scans so far both match up with my lmp. I had one at 7 weeks and one at 13 weeks.
so I calculated that I conceived around 22nd September.

Here are my dates:
lmp: 9/10th Sept
28 Oct: 7 week scan
Conception around 22nd September?

However my period was very light and spotting, is it possible this was actually implantation and the ultrasound is out by few weeks?

ANSWER

Hello
The ultrasound would never be a few weeks off in the first trimester. If the ultrasound showed you were 7 weeks along on Oct 28th, your conception date would be around Sept 23rd.

You would not take into consideration the light period/spotting you had. This would not affect the dating of the pregnancy.

With Regards,
-- Jane RDMS