Home
Back
Perinatology Standard Due Date Formula:
| From: | To: |
The Perinatology Standard Due Date calculation estimates the expected delivery date (EDD) based on the last menstrual period (LMP). This method adds 280 days (40 weeks) to the first day of the last menstrual period, following standard obstetric practice.
The calculator uses the standard obstetric formula:
Where:
Explanation: This calculation assumes a regular 28-day menstrual cycle and ovulation occurring on day 14. The 280 days represents the average human gestation period from the first day of the last menstrual period.
Details: Accurate due date estimation is crucial for proper prenatal care, monitoring fetal development, scheduling important tests, and preparing for delivery. It helps healthcare providers track pregnancy progress and identify potential complications.
Tips: Enter the first day of your last menstrual period in the date field. Ensure the date is accurate for the most reliable due date estimation. This calculation works best for women with regular menstrual cycles.
Q1: Why is the calculation based on LMP rather than conception date?
A: LMP is typically more reliably known than conception date. The standard adds 2 weeks to account for the time between LMP and actual conception.
Q2: How accurate is this due date calculation?
A: Only about 5% of women deliver on their exact due date. Most deliveries occur within 2 weeks before or after the calculated date.
Q3: What if my menstrual cycles are irregular?
A: For irregular cycles, early ultrasound dating is more accurate. This calculation assumes a regular 28-day cycle.
Q4: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, which can be more accurate than LMP-based calculations.
Q5: What is Naegele's Rule?
A: This calculation is based on Naegele's Rule: add 1 year, subtract 3 months, and add 7 days to the first day of LMP, which equals 280 days.