This is an NCLEX review on Naegele’s Rule. Naegele’s Rule is used to calculate a woman’s estimate delivery date (EDD).
In nursing school, you will be required to know how to calculate a woman’s due date by using Naegele’s Rule (also spell Nagele’s). These questions are common on lecture exams and the NCLEX.
When you are done reviewing Naegele’s Rule, don’t forget to take the Naegele’s Rule review quiz.
Lecture on Naegele’s Rule
Naegele’s Rule Nursing NCLEX Review
Key Points about Naegele’s Rule:
- It is used for estimating an expected due date based on the woman’s last menstrual period (LMP).
- It bases it calculation that the woman has a 28 day menstrual cycle (many woman vary) AND that it will be a gestation period of 280 days (40 weeks)… again this varies because gestation is slightly longer for first time mothers. Hence, Naegele’s Rule calculation in JUST an estimation!
- Always give February 28 days (regardless of a leap year…to keep things simple).
- Know which months have 30 days vs 31 days (September, April, June & November have 30 days)
- Remember the mnemonic you may have been taught as a child:
“Thirty days has September,
April, June, and November.
All the rest have thirty-one,
Except for February alone,
Which has but twenty-eight days clear,
And twenty-nine in each leap year.”
Calculation Formula for Naegele’s Rule
- Subtract 3 months from the LMP
- Add 7 Days to the LMP
- Add 1 Year
(use this calculation formula for patients whose LMP falls between April-Dec)
- Add 7 Days to LMP
- Then add 9 months
(use this calculation formula for patients whose LMP falls between January-March rather than the other formula)
*Please watch the lecture video above for why it is best to use these different calculations based on when the LMP falls to prevent errors.
Naegele’s Rule Example & Practice Question
Question 1: LMP: January 5, 2017
+ 7 days
January 12, 2017
EDD: October 12, 2017
Question 2: LMP: September 28, 2016
– 3 months
June 28, 2016
+ 7 days
July 5, 2016
+ 1 year=
EDD: July 5, 2017