1. What is Perinatal EDD Calculation?

The Perinatal Estimated Due Date (EDD) calculation estimates the expected delivery date based on the last menstrual period (LMP). It uses the standard formula of LMP plus 280 days (40 weeks) to determine the due date.

2. How Does the Calculator Work?

The calculator uses the standard perinatal EDD formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — Last Menstrual Period
• \( 280 \) — Standard gestation period in days (40 weeks)

Explanation: This calculation is based on Naegele's rule, which assumes a 28-day menstrual cycle and ovulation occurring on day 14.

3. Importance of EDD Calculation

Details: Accurate EDD calculation is crucial for prenatal care planning, monitoring fetal development, scheduling important tests, and preparing for delivery.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the date field. The calculator will automatically compute your estimated due date by adding 280 days (40 weeks).

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP-based due date?
A: LMP-based due dates are accurate for women with regular 28-day cycles. For irregular cycles, ultrasound dating may be more precise.

Q2: What if I don't know my exact LMP?
A: If LMP is uncertain, an early pregnancy ultrasound (first trimester) provides the most accurate dating.

Q3: Why 280 days specifically?
A: 280 days represents 40 weeks of gestation, calculated from the first day of the last menstrual period rather than conception date.

Q4: Can the due date change during pregnancy?
A: Yes, early ultrasound measurements may lead to adjustment of the EDD, especially if there's significant discrepancy with LMP dating.

Q5: What percentage of babies are born exactly on their due date?
A: Only about 5% of babies are born on their exact due date. Most are born within two weeks before or after the calculated date.