1. What is the Due Date Calculator?

The Due Date Calculator estimates the expected delivery date based on the first day of your last menstrual period (LMP), using the standard 280-day (40-week) pregnancy calculation.

2. How Does the Calculator Work?

The calculator uses the Naegele's rule:

Where:

• \( \text{LMP} \) — First day of last menstrual period
• \( 280 \text{ days} \) — Standard duration of pregnancy (40 weeks)

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

3. Importance of Due Date Calculation

Details: Knowing your estimated due date helps in prenatal care planning, monitoring fetal development, and preparing for delivery. Only about 5% of women deliver on their exact due date.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period. The calculator will show your estimated due date and current gestational age.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculator?
A: It's accurate for women with regular 28-day cycles. Ultrasound dating may be needed for irregular cycles.

Q2: What if I know my conception date?
A: You can calculate by adding 266 days (38 weeks) to the conception date.

Q3: Why 280 days if pregnancy is 9 months?
A: 280 days equals 40 weeks (including the 2 weeks before conception). Actual pregnancy is about 38 weeks from conception.

Q4: What percentage of babies are born on the due date?
A: Only about 5%. Most births occur within 2 weeks before or after the due date.

Q5: How does this differ from ultrasound dating?
A: Early ultrasound (especially first trimester) may provide more accurate dating, particularly if menstrual dates are uncertain.