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Expected Delivery Date Formula:
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The Expected Delivery Date (EDD) is the estimated date when a pregnant woman is likely to give birth. It's calculated based on the first day of the Last Menstrual Period (LMP) and represents approximately 40 weeks of gestation.
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 40 weeks of pregnancy from the LMP.
Details: Accurate EDD calculation is crucial for monitoring fetal development, scheduling prenatal care, determining gestational age, and planning for delivery. It helps healthcare providers track pregnancy milestones 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 EDD calculation. The calculator will provide the estimated due date based on the standard 280-day gestation period.
Q1: How accurate is the EDD calculation?
A: The EDD is an estimate. Only about 5% of women deliver exactly on their due date. Most deliveries occur within 2 weeks before or after the calculated EDD.
Q2: What if my menstrual cycle is irregular?
A: For women with irregular cycles, an early ultrasound (first trimester) provides a more accurate EDD than LMP-based calculation.
Q3: Can the EDD change during pregnancy?
A: Yes, healthcare providers may adjust the EDD based on ultrasound measurements, especially if there's a significant difference from the LMP-based calculation.
Q4: Why is 280 days used instead of 9 months?
A: 280 days equals 40 weeks, which is the standard medical calculation. Calendar months vary in length, so weeks provide a more consistent measurement.
Q5: What is Naegele's Rule?
A: This is the traditional method: Add 7 days to LMP, then subtract 3 months. Our calculator uses the equivalent 280-day calculation for accuracy.