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Conception Date Formula:
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The Accurate Conception Date Calculator determines the most likely date of conception based on ultrasound-adjusted estimated due date (EDD). This method provides more precise conception dating compared to traditional last menstrual period calculations.
The calculator uses the medical formula:
Where:
Explanation: Ultrasound dating in early pregnancy is highly accurate for determining gestational age. Subtracting 266 days (38 weeks) from the EDD provides the most reliable conception date estimate.
Details: Precise conception dating is crucial for accurate pregnancy monitoring, determining fetal development milestones, scheduling prenatal testing, and establishing paternity when needed.
Tips: Enter the ultrasound-adjusted estimated due date provided by your healthcare provider. The calculator will determine the corresponding conception date based on standard gestation periods.
Q1: Why use ultrasound-adjusted EDD instead of LMP?
A: Ultrasound dating in the first trimester is more accurate than last menstrual period (LMP) dating, especially when menstrual cycles are irregular or LMP date is uncertain.
Q2: Is 266 days the exact gestation period for everyone?
A: 266 days represents the average time from conception to delivery. Actual gestation can vary from 259-280 days (37-40 weeks from LMP).
Q3: How accurate is ultrasound for dating pregnancy?
A: First-trimester ultrasound can determine gestational age within ±5-7 days, making it the gold standard for pregnancy dating.
Q4: Can this calculator determine exact date of conception?
A: While highly accurate, it provides the most likely conception date. Actual conception can occur within a 5-day window around this date.
Q5: When is the best time for ultrasound dating?
A: Between 8-13 weeks gestation provides the most accurate dating, as fetal measurements are most consistent during this period.