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El Paso, TX
A 30-year-old female asked:

Are two weeks added to ultrasound gest. age like when calculating from the lmp? eg, u/s on jan 13 estimated 9+1 age. so i conceived roughly nov 9?

1 doctor answer4 doctors weighed in
Dr. David Dinhofer
Radiology 42 years experience
Yes: Ultrasound for pregnancy uses the same 40 week gestation time as OB to be consistent. So, the reference date is the time of the last menstrual period, not ovulation. Honestly, i don't know why the medical community hasn't changed this except that it has been accepted for so long.

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Last updated May 16, 2015

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