1. What is Pregnancy Due Date Calculation?

The pregnancy due date calculation estimates the expected date of delivery based on the first day of the last menstrual period (LMP). This method, known as Naegele's rule, adds 280 days (40 weeks) to the LMP date.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — Last Menstrual Period (first day)
• \( 280 \text{ days} \) — Standard pregnancy duration (40 weeks)

Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The due date represents the end of 40 weeks of gestation.

3. Importance of Due Date Calculation

Details: Accurate due date estimation is crucial for prenatal care planning, fetal growth monitoring, timing of prenatal tests, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period using the date picker. Ensure the date is accurate for the most reliable due date estimation. The calculator will also show your current gestational age in weeks and days.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP method?
A: The LMP method is reasonably accurate for women with regular 28-day cycles. However, first-trimester ultrasound dating is often more precise, especially if cycle length varies.

Q2: What if my cycle is longer or shorter than 28 days?
A: For cycles longer than 28 days, add the extra days to the due date. For shorter cycles, subtract the difference. Consult your healthcare provider for personalized calculation.

Q3: Why 280 days instead of 9 months?
A: Pregnancy is calculated as 40 weeks from LMP, which equals 280 days. This differs from calendar months due to varying month lengths and the way gestational age is measured.

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

Q5: When should I confirm my due date with ultrasound?
A: An ultrasound in the first trimester (6-13 weeks) can provide the most accurate dating. Later ultrasounds are less reliable for establishing due dates.