Ultrasound accuracy dating conceive

Use of the LMP to establish the due date may overestimate the duration of the pregnancy, and can be subject to an error of more than 2 weeks [5-7]. In cases where the date of conception is known precisely, such as with in vitro fertilization, the EDD is calculated by adding 266 days to the date of conception. American College of Obstetricians and Gynecologists. even though they said my baby was 6 days ahead my conception date doesnt change?

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Determining the Estimated Due Date The estimated due date (EDD or EDC) is the date that spontaneous onset of labor is expected to occur. Conceptional age, menstrual age, and ultrasound age: a second-trimester comparison of pregnancies of known conception date with pregnancies dated from the last menstrual period.

The due date may be estimated by adding 280 days ( 9 months and 7 days) to the first day of the last menstrual period (LMP). The accuracy of the EDD derived by this method depends on accurate recall by the mother, assumes regular 28 day cycles, and that ovulation and conception occurs on day 14 of the cycle.

Also, when providers all use the same LMP date, we are using one system that provides a standard convention.

Dating Scans A scan can date the time of conception if you are uncertain of when your baby was conceived.

Examples include if you have irregular menstrual cycles or long menstrual cycles, or if you became pregnant directly after a miscarriage or after extended breastfeeding without menstruating.

“Exercise extreme caution with regard to last menstrual period (LMP) on history taking.Summary statistics for GA using each reference method were determined (n = 131).Correlation between GA determined by ultrasound and ovulation day was excellent (maximum difference 10 days); however, pregnancies dated by ultrasound were 3 days advanced.I know when they use your period they say that the baby wasn't actually conceived until about the 14th day. But I was wondering, when they did my date scan at 8 weeks they said my due date would actually be September 8th.So with the date scan are they saying my baby was actually conceived on December 2nd or on December 16th?I'm curious to know if the first ultrasound is accurate with the conception date they give u? Early ultrasounds are more accurate at determining gestation than later ultrasounds.