1. What is Pregnancy Due Date Calculation?

The pregnancy due date calculation estimates the expected date of delivery (EDD) based on the first day of the last menstrual period (LMP). This method, known as Naegele's rule, adds 280 days (40 weeks) to the LMP date to determine the estimated due date.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

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

Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The calculator also provides current gestational age based on today's date.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for prenatal care planning, fetal growth monitoring, timing of prenatal tests, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the date field. The calculator will provide your estimated due date and current gestational age. For best accuracy, use the exact date of your LMP.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP method?
A: The LMP method is accurate for women with regular 28-day cycles. For irregular cycles, ultrasound dating in early pregnancy may be more accurate.

Q2: What if I don't know my LMP?
A: If you're unsure of your LMP, an early pregnancy ultrasound (before 14 weeks) can provide accurate dating based on fetal measurements.

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: 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 2 weeks before or after the estimated due date.

Q5: Can the due date change during pregnancy?
A: Yes, due dates may be adjusted based on early ultrasound measurements, especially if there's a significant difference from LMP-based calculation.