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Pregnancy Due Date Formula:
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The Pregnancy Due Date Calculator estimates the expected delivery date (EDD) based on the first day of the last menstrual period (LMP). This calculation uses Naegele's rule, which adds 280 days (40 weeks) to the LMP date.
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 due date represents the estimated date when pregnancy reaches 40 weeks gestation.
Details: Accurate due date estimation is crucial for monitoring fetal development, scheduling prenatal care, determining appropriate timing for tests and procedures, and preparing for delivery.
Tips: Enter the first day of your last menstrual period. Ensure the date is accurate as this forms the basis for all subsequent pregnancy dating and monitoring.
Q1: How accurate is this due date calculation?
A: This method is accurate for women with regular 28-day cycles. Only about 5% of babies are born exactly on their due date, with most deliveries occurring within 2 weeks before or after.
Q2: What if my menstrual cycle is longer or shorter than 28 days?
A: For irregular cycles, the due date may need adjustment. Women with longer cycles may ovulate later, which would make the actual due date later than calculated.
Q3: Can the due date change during pregnancy?
A: Yes, healthcare providers may adjust the due date based on early ultrasound measurements, which are most accurate in the first trimester.
Q4: What is considered full-term pregnancy?
A: Full-term is between 39 weeks 0 days and 40 weeks 6 days. Early term is 37-38 weeks, late term is 41-41+6 weeks, and post-term is 42+ weeks.
Q5: Should I rely solely on this calculator for medical decisions?
A: No, this calculator provides an estimate. Always consult with your healthcare provider for accurate pregnancy dating and prenatal care guidance.