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Pregnancy Calculation Formula:
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The When Did I Get Pregnant Exactly Calculator helps determine the approximate conception date based on your estimated due date (EDD). This calculation uses the standard medical formula that subtracts 266 days from your due date to estimate when conception likely occurred.
The calculator uses the pregnancy calculation formula:
Where:
Explanation: This calculation assumes a 40-week pregnancy from the first day of your last menstrual period, with conception typically occurring around 2 weeks after that date.
Details: Knowing your conception date helps with accurate pregnancy dating, understanding fetal development milestones, and can be important for medical assessments and prenatal care planning.
Tips: Enter your estimated due date as provided by your healthcare provider. This is typically calculated from your last menstrual period or early ultrasound measurements.
Q1: How accurate is this calculation?
A: This provides an estimate. Actual conception dates can vary due to individual differences in cycle length and ovulation timing.
Q2: Why 266 days instead of 280 days?
A: 280 days is from last menstrual period, while 266 days is from actual conception. Conception typically occurs about 14 days after the start of your last period.
Q3: What if I know my ovulation date?
A: If you know your exact ovulation date, that is your most accurate conception date, as conception typically occurs within 24 hours of ovulation.
Q4: Can ultrasound change my due date?
A: Yes, early pregnancy ultrasounds (especially first trimester) are very accurate and may adjust your estimated due date.
Q5: What factors can affect the accuracy?
A: Irregular menstrual cycles, uncertain last menstrual period dates, and variations in implantation timing can affect accuracy.