1. What is the Expected Due Date Calculation?

The expected due date is calculated as 280 days (40 weeks) from the first day of the last menstrual period (LMP). This is known as Naegele's rule and is the standard method for estimating delivery dates.

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 gestation

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

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for proper prenatal care, monitoring fetal development, and determining the timing of important tests and interventions during pregnancy.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format YYYY-MM-DD. The calculator will show both the expected due date and current gestational age.

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 cycles aren't 28 days?
A: For irregular or longer cycles, the due date may need adjustment. Consult your healthcare provider.

Q3: Can ultrasound change my due date?
A: Early ultrasound (especially first trimester) may adjust the due date if it differs significantly from LMP-based calculation.

Q4: Why 280 days?
A: This represents 40 weeks from LMP, which is approximately 38 weeks from conception (the actual gestation period).

Q5: What's considered full term?
A: 37-42 weeks is considered term. Before 37 weeks is preterm, after 42 weeks is post-term.