Expected date of delivery is calculated by using ?

Appeared in: RRB Nsg. Superintendent-21 July 2019 (Shift-2nd)

Explanation

Naegele's formula is the standard method used to estimate the Expected Date of Delivery (EDD) based on the last menstrual period (LMP).
The calculation involves adding 9 months and 7 days to the first day of the woman's LMP.
An alternative calculation is to subtract 3 months from the LMP and then add 7 days and 1 year.
This rule is based on the assumption of a normal 28-day menstrual cycle and a 280-day (40-week) gestation period.

Option A: Wood's formula is not used for calculating the EDD. This option likely causes confusion with Wood's corkscrew maneuver.
Option C: Robert's formula is not a recognized formula for calculating the EDD. This is likely a confusion with the McRoberts maneuver.
Option D: Johnson's formula is used to estimate fetal weight, not the delivery date.

Visual 1: Infographic - A step-by-step visual guide showing how to calculate the EDD using Naegele's rule with a calendar example. It would show starting from the LMP date, counting back 3 months, and adding 7 days.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of Expected Date of Delivery (EDD) as background academic context rather than a clinical decision trigger.
Accurately determining the EDD is crucial for scheduling antenatal appointments, performing timely screenings (like for gestational diabetes or Group B Streptococcus), and making decisions about managing post-term pregnancies.
Nurses are often the first point of contact for pregnant women and are responsible for calculating the initial EDD and educating the patient about her pregnancy timeline.
What if the patient has an irregular menstrual cycle or is unsure of her LMP? In this case, Naegele's rule is unreliable. A first-trimester ultrasound is the most accurate method to establish the gestational age and EDD.

How to Approach the Question

Identify the core question: The question asks for the specific formula used to calculate the expected date of delivery (EDD).
This is a factual recall question. Access your knowledge of common obstetrical calculations.
Evaluate each option:
Recall or deduce that Naegele's formula is directly associated with calculating the due date from the Last Menstrual Period (LMP).
Recognize that Johnson's formula relates to fetal weight estimation.
Identify that Wood's and Robert's formulas are not standard for EDD and are likely distractors related to shoulder dystocia maneuvers (Wood's corkscrew and McRoberts).

Concept Tested & Keywords

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