1. What is the Due Date Calculation?

The due date calculation estimates the expected date of delivery (EDD) by adding 280 days (40 weeks) to the first day of the last menstrual period (LMP). This is based on the typical 28-day menstrual cycle and ovulation occurring on day 14.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• LMP — First day of last menstrual period
• 280 days — Equivalent to 40 weeks of gestation

Explanation: This calculation (Naegele's rule) assumes conception occurred approximately 14 days after the LMP in a regular 28-day cycle.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for prenatal care scheduling, monitoring fetal development, and determining if a pregnancy is post-term.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format YYYY-MM-DD. The calculator will add 280 days to estimate your due date.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is this calculation?
A: Only about 5% of women deliver on their exact due date. Most deliver within 2 weeks before or after.

Q2: What if my cycle isn't 28 days?
A: For irregular cycles, an ultrasound dating scan in the first trimester is more accurate.

Q3: Why 280 days if pregnancy is 9 months?
A: Pregnancy is actually about 9.5 lunar months (4 weeks each). 280 days equals 40 weeks.

Q4: When should I see my doctor?
A: Schedule your first prenatal visit as soon as you have a positive pregnancy test.

Q5: Can the due date change?
A: Yes, your provider may adjust it based on early ultrasound measurements.