6 doctors weighed in:
What is more accurate in dating day of conception, going 14 days after the last period, or the 7 week ultrasound dating?
6 doctors weighed in

Dr. Joseph Pena
Fertility Medicine
5 doctors agree
In brief: Depends
If normal pregnancy, 7 week ultrasound should be consistent (+/- 3 days) with estimated gestation by last menstrual period (assumes ovulation 14 days after lmp).
This may be modified if pregnancy occurs after infertility treatment which can alter menstrual cycle. In such cases of insemination or ivf, dating may be more accurately calculated based on ovulation.

In brief: Depends
If normal pregnancy, 7 week ultrasound should be consistent (+/- 3 days) with estimated gestation by last menstrual period (assumes ovulation 14 days after lmp).
This may be modified if pregnancy occurs after infertility treatment which can alter menstrual cycle. In such cases of insemination or ivf, dating may be more accurately calculated based on ovulation.
Dr. Joseph Pena
Dr. Joseph Pena
Thank
Dr. Luis Villaplana
Internal Medicine
In brief: ULTRASOUND IS
Typically the most accurate of the 2.

In brief: ULTRASOUND IS
Typically the most accurate of the 2.
Dr. Luis Villaplana
Dr. Luis Villaplana
Thank
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