Accuracy sonogram dating
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.
303, February 2014 Society of Obstetricians and Gynaecologists of Canada. 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. Multifetal gestations: twin, triplet, and higher-order multifetal pregnancies. Page JM, The risk of stillbirth and infant death by each additional week of expectant management in twin pregnancies.