2. Pregnant women generally want to know
when the baby is coming or the “due date”.
The ability to detect the date of
confinement or delivery is an essential
nursing competency needed by anyone
dealing with maternity clients.
The date of delivery has been called the
“Estimated/Expected Date of Confinement
(EDC). But the concept of confinement is
negative so the trend now is to refer to it
as “Estimated/Expected Date of Delivery
(EDD).
3. The NAEGELE’S RULE is the most common
method of determining the EDD.
PROCEDURE:
1. Determine the normal Last Menstrual Period
(LMP).
The date of the onset of the last normal menstrual
period is of clinical importance for determining the
EDD and fetal age. For this reason the LMP should
be checked for normality, regularity and character.
It should not be confused with implantation
bleeding which is a slight blood loss when fertilized
ovum embeds onto the wall of the uterus.
4. 2. Consider the FIRST DAY of the LMP.
For example: LMP is July 12-17, 2023
First day of LMP is July 12, 2023.
3. Consider the month in numerical term.
For example: July = 7 August = 8
September = 9 October = 10
Numerical term of July is 7
7 12 2023
5. 4. Use the Naegele’s Formula:
(-3mos + 7 days + 1 year) or subtract 3
months, add 7 days to the first day of LMP;
add 1 year (except for the first three
months of the year which is January,
February and March).
For example: LMP is July 12-17, 2023
7 12 2023
-3 +7 +1
4 19 2024
EDD is April 19, 2024
6. 5. Use the Naegele’s Formula:
For the first three months of the year, add
12 to the numerical value of the month.
For example: January 1 + 12 = 13
February 2 + 12 = 14
March 3 + 12 = 15
7. ➢ For example: LMP is February 2-6, 2023
Numerical value of February is 14
(2+12=14)
14 2 2023
-3 +7______
11 9 2023
EDD is November 9, 2023
8. Note: The Naegele’s Rule is just an
estimate.
It is said that 40% of all the babies
arrive on time using this rule, whereas
60% appear 1 to 7 days early or late.
To count from the first day of LMP gives us
the GESTATIONAL AGE or MENSTRUAL AGE.
At the time of EDD, the baby is 40 weeks.
This is the average gestational or menstrual
age.
9. Naegele’s Rule
- the most common method of determining the EDD.
For the first three months of the year:
+9 months +7 days
Ex: LMP March 5, 2023
03 – 05 – 2023
+ 9 - +7______
12 12 2023 December 12, 2023
From months April to December
-3 month +7 days +1 year
May 15, 2023
05 – 15 – 2023
- 3 +7 +1
2 22 2024 February 22, 2024
11. AOG – Age of Gestational- LMP – March 17, 2023
DOC- Dec. 20, 2022
March – 14
April – 30
May 31
June 30
July 31 278/7 = 39 5 weeks
August 31
September 30
October 31
November 30
December 20
278
