A 23-year-old female asked:
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can 1st trimester u/s be off 3 weeks in gestational age and in conception? (1st trimester) even if they have been pretty consistent in the pregnany

1 doctor answer
Dr. David Doucette
38 years experience Obstetrics and Gynecology
Not usually: Generally, the best ultrasound for dating is an early first trimester ultrasound. It is unlikely to be off by that much from where the actual pregnancy dates are, but it might be off from your menstrually calculated due date due to issues with when your last period was.
Answered on Feb 24, 2014
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