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A member asked:
What changes a due date? and why is the first trimester ultrasound more accurate than the second trimester ultrasound?
A doctor has provided 1 answer
Ultrasound dating.: First trimester ultrasound is by far the most accurate in determining the precise due date (+/- 3-7 days, depending on exactly when it is performed). Second trimester sonograms are less accurate but still helpful in pegging down the due date within +/-7-12 days. Third trimester scans are not very accurate in dating the pregnancy, as growth varies (+/- 14-21 days). Menstrual dating is not very good.
Answered 12/9/2013
5.3k views
Related Questions
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