Estimated date of delivery is calculated by:

Question

A. Adding 7 days to LMP and subtracting 3 months
B. Adding 9 months to the date of LMP
C. Most accurately by ultrasound examination
D. A & C

Answer 1

ANS: A
An estimated date of delivery (EDD) is projected at this time by using the last menstrual period (LMP). This estimation can be made either with a pregnancy wheel or calculator or by applying Naegele's rule of adding 7 days to the first day of the LMP and then subtracting 3 months (Cunningham et al., 2010). This method of estimating the EDD depends on the woman having regular menstrual cycles of 28, plus or minus 7 days. If the EDD cannot be accurately estimated by Naegele's rule, an early ultrasound is recommended because of the linkage of specific prenatal interventions with gestational dating of the pregnancy. The EDD should be updated throughout the pregnancy for confirmation of dates by determining when quickening occurs, when fetal heart tone (FHTs) are first auscultated, when the fundal height is at the umbilicus, and, most accurately, through an ultrasound estimation at 16 to 20 weeks.