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Due Date Calculation:
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The Due Date Calculator estimates the expected delivery date based on the known date of ovulation. This method is particularly accurate for women who track their ovulation through fertility awareness methods or ovulation predictor kits.
The calculator uses the following calculation:
Where:
Explanation: Pregnancy typically lasts about 266 days (38 weeks) from conception. Since ovulation usually occurs about 14 days before the next menstrual period, this method provides a more accurate estimate than calculations based on the last menstrual period.
Details: Knowing the estimated due date helps healthcare providers monitor fetal development, schedule important prenatal tests, and prepare for delivery. It also helps expectant parents plan for the baby's arrival.
Tips: Enter the exact date of ovulation if known. For best results, use ovulation dates confirmed through basal body temperature charting, ovulation predictor kits, or ultrasound monitoring.
Q1: How accurate is this calculation?
A: When the exact ovulation date is known, this method is very accurate. Only about 5% of women deliver on their exact due date, but most deliver within 2 weeks before or after.
Q2: Why 266 days instead of 280 days?
A: 280 days (40 weeks) is calculated from the first day of the last menstrual period (LMP), while 266 days (38 weeks) is calculated from conception/ovulation.
Q3: What if I don't know my exact ovulation date?
A: If you don't know your ovulation date, you can use a calculator based on your last menstrual period instead.
Q4: Does this work for IVF pregnancies?
A: Yes, for IVF pregnancies where the conception date is precisely known, this method is very accurate.
Q5: Can the due date change?
A: Early ultrasound measurements may adjust the due date, especially if they differ significantly from the ovulation-based calculation.