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Ovulation Date Based Calculation:
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The Ovulation Date Based Pregnancy Calculator estimates the due date by adding 266 days to the known ovulation date. This method provides a more accurate due date calculation compared to last menstrual period (LMP) based calculations, especially for women with irregular cycles.
The calculator uses the simple formula:
Explanation: This calculation is based on the typical human gestation period of 266 days (38 weeks) from ovulation to delivery. The 266-day period accounts for the time from conception to birth.
Details: Using ovulation date for due date calculation is particularly valuable for women who track their ovulation through methods like basal body temperature charting, ovulation predictor kits, or fertility monitoring. It provides a more precise due date than LMP-based calculations.
Tips: Enter your known ovulation date in the date picker. The calculator will automatically compute your estimated due date by adding 266 days to your ovulation date.
Q1: Why 266 days instead of 280 days?
A: 280 days is calculated from the first day of the last menstrual period (LMP), while 266 days is calculated from ovulation/conception. Since ovulation typically occurs about 14 days after the start of menstruation, both methods should yield similar due dates.
Q2: How accurate is ovulation date based calculation?
A: This method is very accurate if you know your exact ovulation date. It's often more precise than LMP-based calculations, especially for women with irregular cycles.
Q3: What if I don't know my exact ovulation date?
A: If you're unsure of your ovulation date, use our Last Menstrual Period (LMP) based pregnancy calculator instead, which estimates based on your last period start date.
Q4: Can due dates change during pregnancy?
A: Yes, healthcare providers may adjust due dates based on early ultrasound measurements, which can be very accurate in the first trimester.
Q5: Is every pregnancy exactly 266 days?
A: No, pregnancy duration can vary. Only about 5% of women deliver on their exact due date. Most deliveries occur within two weeks before or after the estimated due date.