Mother's last LMP is Dec. 7. Calculate her EDD?

Appeared in: DSSSB Public Health Nurse - 2015

Explanation

The standard method for calculating the Estimated Date of Delivery (EDD) is Naegele's Rule.
The formula for Naegele's Rule is: EDD = Last Menstrual Period (LMP) + 9 months + 7 days.
The LMP is given as December 7.
Step 1: Add 9 months to December 7, which results in September 7 of the next year.
Step 2: Add 7 days to September 7, which results in September 14.
Thus, the calculated EDD is September 14.

Option B: This date is incorrect. It may result from an error in counting the months, possibly by adding 11 months instead of 9.
Option C: This date is incorrect. It likely results from an error in adding the days, for instance, adding 20 days (7+13) instead of just 7 days to September 7.
Option D: This date is incorrect and represents a significant miscalculation of both months and days.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Calculation of Estimated Date of Delivery (EDD) using Naegele's Rule as background academic context rather than a clinical decision trigger.
Accurately calculating the EDD is a fundamental nursing skill in antenatal care. It is crucial for scheduling prenatal tests, monitoring fetal growth, and making timely decisions regarding interventions like induction of labor if the pregnancy goes post-term.
The EDD provides a timeline for the entire pregnancy, helping the healthcare team and the expectant mother to plan for a safe delivery and prepare for the newborn's arrival.
What if the mother has an irregular menstrual cycle? If a woman's cycle is significantly longer or shorter than the average 28 days, Naegele's rule may be less accurate. In such cases, an early first-trimester ultrasound is the most reliable method for determining the gestational age and establishing a more accurate EDD.

How to Approach the Question

First, identify the key information provided in the question: the Last Menstrual Period (LMP) is December 7.
Recall the standard formula for calculating the Estimated Date of Delivery (EDD), which is Naegele's Rule.
State the formula: EDD = LMP + 9 months + 7 days.
Apply the formula step-by-step. First, add 9 calendar months to the LMP date.
Next, add 7 days to the date obtained in the previous step.
Compare your final calculated date with the given options to find the correct answer.

Concept Tested & Keywords

Concept Tested: Calculation of Estimated Date of Delivery (EDD) using Naegele's Rule
Stem keywords: LMP, Dec. 7, Calculate, EDD
Lead-in keywords: Calculate

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E6 Comprehensive Textbook of Community Health Nursing for BSc Nursing Students Part 2 — Subpart A (pp 1-275 of 550) p. 195-197

E6 Obstetrics Williams p. 19-35

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