1. What is EDD LMP Calculation?

The EDD LMP (Estimated Due Date based on Last Menstrual Period) calculation estimates the expected delivery date by adding 280 days (40 weeks) to the first day of the last menstrual period. This is the most common method used to calculate pregnancy due dates.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — Last Menstrual Period (first day)
• \( 280 \) — Standard pregnancy duration in days (40 weeks)

Explanation: This calculation is based on the assumption of a regular 28-day menstrual cycle with ovulation occurring on day 14.

3. Importance of Due Date Calculation

Details: Accurate due date calculation is essential for proper prenatal care, 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. Ensure the date is accurate for the most reliable due date estimation.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP method?
A: The LMP method is generally 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 LMP exactly?
A: If you're unsure of your LMP, an early pregnancy ultrasound (first trimester) can provide a more accurate due date.

Q3: Why 280 days instead of 9 months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This accounts for the fact that conception typically occurs about 2 weeks after LMP.

Q4: Can my due date change?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements or if the LMP date seems inconsistent with clinical findings.

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