1. What is the 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, called Naegele's rule, assumes a standard 280-day (40-week) pregnancy.

2. How Does the Calculator Work?

The calculator uses the standard due date formula:

Where:

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

Explanation: The calculation adds 280 days (40 weeks) to the first day of your last menstrual period. This is based on the average length of human gestation.

3. Importance of Due Date Estimation

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

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the format MM/DD/YYYY. The calculator will show your estimated due date and current pregnancy progress.

5. Frequently Asked Questions (FAQ)

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

Q2: What if I don't know my LMP?
A: An ultrasound measurement in early pregnancy (especially first trimester) can provide a reliable due date estimate.

Q3: Does this work for irregular cycles?
A: The calculation assumes a 28-day cycle. If your cycles are significantly longer or irregular, the due date may need adjustment.

Q4: What's the difference between gestational age and fetal age?
A: Gestational age counts from LMP (about 2 weeks before conception). Fetal age counts from actual conception and is about 2 weeks less.

Q5: When should I see a doctor after calculating my due date?
A: Schedule your first prenatal visit as soon as you get a positive pregnancy test, typically around 8 weeks gestational age.