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Expected Due Date Formula:
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The Expected Due Date (EDD) is the estimated date when a pregnant woman is likely to give birth. It is calculated based on the first day of the last menstrual period (LMP) plus 280 days, which corresponds to 40 weeks of gestation.
The calculator uses the standard due date formula:
Where:
Explanation: This calculation is based on Naegele's rule, which assumes a regular 28-day menstrual cycle and ovulation occurring on day 14.
Details: Accurate due date calculation is essential for proper prenatal care, monitoring fetal development, scheduling important tests, and preparing for delivery.
Tips: Enter the first day of your last menstrual period in the date field. The calculator will automatically compute your expected due date by adding 280 days (40 weeks).
Q1: How accurate is this due date calculation?
A: This method provides a good estimate, but only about 5% of women actually deliver on their exact due date. Most deliveries occur within two weeks before or after the calculated date.
Q2: What if my menstrual cycle is irregular?
A: For women with irregular cycles, an early ultrasound (first trimester) provides a more accurate due date estimation than LMP-based calculation.
Q3: Why 280 days specifically?
A: 280 days represents 40 weeks of pregnancy, calculated from the first day of the last menstrual period rather than from conception.
Q4: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, especially if there's a significant difference from the LMP-based calculation.
Q5: What percentage of babies are born on their due date?
A: Only about 4-5% of babies are born exactly on their due date. About 80% are born within two weeks of the due date.