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A member asked:

On the thirteenth i had an ultrasound stating i was 8 wks and 2 days. last menstrual beginning of august with irregular cycle. when was my conception?

A doctor has provided 1 answer

Around August 30: Subtracting 2 weeks from the date given will give you time from conception. Therefore 6 weeks 2 days before Oct. 13 is Aug. 30. By convention we count weeks of pregnancy from your last period, assuming a normal 28 day cycle. Obviously, this will not match up to your actual period if you are irregular.

Answered 10/17/2014

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