1. What is Perinatology Calculator II?

Perinatology Calculator II calculates the estimated due date (EDD) based on the last menstrual period (LMP) using the standard formula of LMP + 280 days. This is a fundamental tool in obstetric care for pregnancy dating and management.

2. How Does the Calculator Work?

The calculator uses the standard obstetric formula:

Where:

• \( EDD \) — Estimated Due Date
• \( LMP \) — Last Menstrual Period
• \( 280 \) — Standard gestation period in days (40 weeks)

Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The 280 days represent the standard 40-week gestation period.

3. Importance of EDD Calculation

Details: Accurate EDD calculation is crucial for proper prenatal care, monitoring fetal development, scheduling important tests, and determining the optimal time for delivery.

4. Using the Calculator

Tips: Enter the first day of your last menstrual period in the date field. Ensure the date is accurate for the most reliable EDD calculation.

5. Frequently Asked Questions (FAQ)

Q1: How accurate is the LMP method?
A: The LMP method is reasonably accurate for women with regular menstrual cycles. For irregular cycles, ultrasound dating is more reliable.

Q2: What if I don't know my LMP?
A: If LMP is unknown, an early pregnancy ultrasound (first trimester) provides the most accurate dating.

Q3: Why 280 days specifically?
A: 280 days represents 40 weeks of gestation, calculated from the first day of the last menstrual period rather than conception date.

Q4: Can the EDD change during pregnancy?
A: Yes, EDD may be adjusted based on early ultrasound measurements, especially if there's a significant discrepancy with LMP-based calculation.

Q5: What percentage of babies are born on their EDD?
A: Only about 4-5% of babies are born exactly on their EDD. Most deliveries occur within two weeks before or after the calculated date.