📚📆 Estimation of EDD (Expected Date of Delivery) and Gestational Age

📘 Highly Important for GNM/BSc Nursing, NHM, AIIMS, NORCET, GPSC & Midwifery/Obstetric Nursing Exams

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✅ 1. Introduction / Definition:

Estimated Date of Delivery (EDD) is the predicted date when a pregnant woman is expected to give birth.
Gestational Age is the duration of pregnancy measured in weeks from the first day of the Last Menstrual Period (LMP).

“EDD is calculated to guide antenatal care, plan delivery, and monitor fetal development based on gestational age.”

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✅ 2. Importance of Estimating EDD and Gestational Age:

• To determine trimester-specific care
• To plan for prenatal tests, ultrasounds, and delivery
• To monitor fetal growth and development
• To identify preterm or post-term pregnancies
• Helps assess fetal viability and maturity

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✅ 3. Methods for Estimating EDD:

🔹 A. Naegele’s Rule (For regular 28-day cycles)

EDD = LMP + 9 months + 7 days

Example:
LMP = 10th January
EDD = 10th October + 7 days = 17th October

Adjust year if needed (e.g., LMP in November or December)

🔹 B. Pregnancy Wheel / Obstetric Calculator

• Rotate wheel to LMP date → directly gives EDD
• Also shows trimester milestones

🔹 C. Ultrasound Dating (USG)

• Most accurate when done in 1st trimester
• Based on Crown-Rump Length (CRL)
• Adjusts gestational age if discrepancy > 7 days

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✅ 4. Calculation of Gestational Age:

Method	Description
From LMP	Count weeks from the first day of LMP to current date
Fundal Height	After 20 weeks, fundal height (in cm) ≈ gestational age (in weeks)
Ultrasound	CRL (1st trimester), Biparietal diameter (BPD), Femur length in 2nd & 3rd trimester
Date of quickening	Fetal movement felt at ~18–20 weeks (multipara: ~16 weeks)

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✅ 5. Trimester Classification:

Trimester	Duration
1st Trimester	0 – 12 weeks
2nd Trimester	13 – 28 weeks
3rd Trimester	29 – 40 weeks

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✅ 6. Fundal Height and Gestational Age:

Fundal Height	Corresponding GA
Just above pubic symphysis	~12 weeks
Midway between pubis and umbilicus	~16 weeks
At umbilicus	~20 weeks
Xiphisternum	~36 weeks
Drops down after 36 weeks due to engagement	~38–40 weeks

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✅ 7. Nursing Responsibilities:

• Accurately record LMP and calculate EDD at first ANC visit
• Use Naegele’s rule or pregnancy wheel
• Monitor fundal height to track fetal growth
• Educate mother on EDD, fetal development, and expected milestones
• Refer for USG if uncertain dates or irregular cycles

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✅ 8. Golden One-Liners for Quick Revision:

• Naegele’s Rule = LMP + 9 months + 7 days
• Gestational age = weeks from LMP to today
• First trimester USG is the most accurate method
• Fundal height in cm ≈ gestational age in weeks (after 20 weeks)
• Normal pregnancy duration = 280 days / 40 weeks

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✅ 9. MCQs for Practice:

Q1. Which formula is used to estimate the EDD?
a) Apgar formula
✅ b) Naegele’s rule
c) Parikh’s rule
d) BMI calculation

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Q2. If LMP is 5th February, what is the EDD?
a) 5th October
b) 12th November
✅ c) 12th November
d) 15th December

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Q3. At what week does the fundus reach the umbilicus?
a) 12 weeks
b) 16 weeks
✅ c) 20 weeks
d) 24 weeks

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Q4. First trimester is from:
a) 0–8 weeks
✅ b) 0–12 weeks
c) 0–14 weeks
d) 0–16 weeks

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Q5. The most accurate method to estimate gestational age is:
a) LMP
b) Fundal height
✅ c) First trimester ultrasound
d) Fetal movement