1. What is the Due Date Calculator?

The Pregnancy Due Date Calculator estimates the expected delivery date based on the first day of your last menstrual period (LMP). This method, called Naegele's rule, is the standard way to calculate due dates in pregnancy.

2. How Does the Calculator Work?

The calculator uses the following formula:

Where:

• LMP — First day of last menstrual period
• 280 days — Average length of human pregnancy (40 weeks)

Explanation: The calculation assumes a regular 28-day menstrual cycle with ovulation occurring on day 14. Actual delivery dates may vary by ±2 weeks.

3. Importance of Due Date Calculation

Details: Knowing your estimated due date helps healthcare providers monitor fetal development, schedule important tests, and determine if the pregnancy is progressing normally.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period (LMP) in the format YYYY-MM-DD. Make sure to use the first day of bleeding, not the last day.

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 calculation may need adjustment. Consult your healthcare provider.

Q3: When will my doctor confirm the due date?
A: An ultrasound in the first trimester can provide a more accurate estimate based on fetal measurements.

Q4: Can the due date change?
A: Yes, early ultrasound measurements may lead to adjustment of the due date, especially if they differ significantly from LMP-based calculation.

Q5: What if I don't know my LMP?
A: If you don't know your LMP, an ultrasound can estimate gestational age and due date based on fetal size.