Pregnancy+dating


 * Establishing Due Date Per 2014 ACOG Recommendation **
 * 1. __Agreement is needed between providers and patient__**

2**. __Last Menstrual Period (LMP) is used to estimate EDD when the following criteria are met:__**
 * Remembered accurately per patient
 * Menses regular and monthly
 * Not on hormonal contraception at the time or just before the last period
 * Ultrasound dates are consistent with the LMP (see below)

3. **__Earlier ultrasounds are almost always more accurate for establishing due date than later ultrasounds__**
 * Exception: Ultrasounds with measurement of the embryo crown rump length (CRL) are more accurate than gestational sac measurements—a 7 week CRL would be used over a 5 week gestational sac measurement
 * If a clinic or informal ultrasound seems inconsistent and a slightly later formal ultrasound exists, it is reasonable to use the later, formal ultrasound as less likely to have clinician error
 * Clinical situation and serial fetal growth ultrasounds may need to be considered In establishing the best EDD for a pregnancy being dated in the late second and third trimester

Based on ACOG Committee Opinion October 20, 2014
 * __Criteria For Changing EDD established by reliable LMP because of ultrasound results__**


 * **EGA by LMP** ||  **Use ultrasound if difference**  ||
 * < 9 weeks ||  > 5 days  ||
 * 9w0d – 15w6d ||  > 7 days  ||
 * 16w0d – 21w6d ||  >10 days  ||
 * 22w0d-27w6d ||  >14 days  ||
 * __>__28 weeks ||  >21 days  ||