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A member asked:
Can the ultrasound be off by 8 weeks in the 2nd trimester?i mean if all ultrasounds match with the dates the preg. can actually be further along?
5 doctors weighed in across 3 answers
Very unlikely: ultrasound should be reliable within 2 weeks at this point, 8 weeks is very improbable
Answered 8/26/2014
3.8k views
One week max: I think 8 weeks off between dates and ultrasound is unlikely. The maximum I've read in studies so far has been 6 days off with accurate dates. Are you sure when your last menstrual period began?
Answered 8/14/2018
3.8k views
Due date & Ultrasoun: Earlier ultrasounds are more accurate for predicting the due date, still it could be off by 1 & half wk, between 18-28 wks the margin of error increases to 2 wks and after that up to 3 wks but not more than that. That's why doctors will usually use the dates and measurements from the first ultrasound of the pregnancy as a reference.
Answered 8/26/2014
3.8k views
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