1. What is the EDD Calculation?

The Estimated Due Date (EDD) calculation, also known as Naegele's rule, estimates the delivery date by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP). This is based on the average human gestation period.

2. How Does the Calculator Work?

The calculator uses the standard formula:

Where:

• \( LMP \) — First day of last menstrual period
• \( 280 \text{ days} \) — Equivalent to 40 weeks gestation

Note: This calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14.

3. Importance of EDD Calculation

Details: The EDD helps healthcare providers monitor fetal growth, schedule important prenatal tests, and determine if pregnancy is progressing normally. It's also used to assess prematurity or postmaturity.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format YYYY-MM-DD. The calculator will display your estimated due date and current gestational age.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the EDD calculation?
A: Only about 4% of women deliver on their EDD. Most deliver within 2 weeks before or after the estimated date.

Q2: What if my cycles aren't regular?
A: For women with irregular cycles, an early ultrasound provides a more accurate dating than LMP-based calculation.

Q3: Why 280 days?
A: This accounts for the average time from the first day of the last period to delivery (2 weeks before conception + 38 weeks gestation).

Q4: Can the EDD change?
A: Yes, early ultrasound measurements may lead to adjustment of the EDD, especially if they differ significantly from the LMP-based calculation.

Q5: What's considered full term?
A: Between 37 weeks 0 days and 41 weeks 6 days. Babies born before 37 weeks are preterm, after 42 weeks are postterm.