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A member asked:
If lmp and 12 week ultrasound correlate, would the u/s be considered more accurate since the lmp is known? or is there still 1 week margin of error?
2 doctors weighed in across 2 answers
+/-1 week.: First trimester sonography is more accurate than even certain menstrual dates due to inherent variation in ovulation. The degree of accuracy at 12 weeks is within a week of the true due date. Take Folic Acid 1-5 mg daily and good luck!
Answered 6/25/2014
5.2k views
LMP for dating : If in the first trimester, we go with the LMP unless the sono is over a week off. I we give the ultrasound date, but say "consistent with dates" the and still use the LMP date.
Answered 2/13/2015
5.2k views
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