2 doctors weighed in:

How accurate are ultrasounds at 12 weeks. is it possible to be twelve weeks pregnant and bby measure at 14 weeks?

2 doctors weighed in
Dr. Gerard Honore
Fertility Medicine

In brief: Very

A technically good scan by a proficient sonographer or physician will be accurate to less than 1 week in the first trimester. If a 12 week scan is technically good and is interpreted correctly, it should not be possible to be off by that much; meaning the ultrasound dates are likely correct.

In brief: Very

A technically good scan by a proficient sonographer or physician will be accurate to less than 1 week in the first trimester. If a 12 week scan is technically good and is interpreted correctly, it should not be possible to be off by that much; meaning the ultrasound dates are likely correct.
Thank
Dr. Joseph Magoun
Family Medicine

In brief: Ultrasound

The earlier an ultrasound is performed in pregnancy, the more accurate is the dating.
The due date likely won't be changed if mom is sure about her last period and the dates aren't more than 2 weeks different at that stage

In brief: Ultrasound

The earlier an ultrasound is performed in pregnancy, the more accurate is the dating.
The due date likely won't be changed if mom is sure about her last period and the dates aren't more than 2 weeks different at that stage
Thank
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