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Conception Timing Formula:
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The conception timing calculation estimates when fertilization likely occurred based on your last menstrual period and typical cycle length. This helps determine the most probable date of conception for pregnancy dating.
The calculator uses the conception timing formula:
Where:
Explanation: This calculation assumes ovulation occurs approximately 14 days before your next period. By subtracting 14 from your cycle length, we determine how many days after your LMP ovulation likely occurred.
Details: Knowing your conception date is important for accurate pregnancy dating, understanding fetal development milestones, and planning prenatal care appointments and tests.
Tips: Enter your last menstrual period date and typical cycle length. Most women have cycles between 21-45 days, with 28 days being average. Use your most consistent cycle length for best accuracy.
Q1: How accurate is this calculation?
A: This provides an estimate. Actual conception can vary by a few days due to sperm survival and ovulation timing variations.
Q2: What if my cycle length varies?
A: Use your average cycle length over the past 3-6 months. If cycles are very irregular, consult a healthcare provider for more accurate dating.
Q3: Why subtract 14 days?
A: The luteal phase (time between ovulation and next period) is typically 14 days for most women, though it can range from 12-16 days.
Q4: Can I get pregnant outside this window?
A: Yes, sperm can survive up to 5 days, so the fertile window typically spans 5-6 days before ovulation through ovulation day.
Q5: How does this relate to gestational age?
A: Pregnancy is dated from the first day of your last menstrual period, which is typically about 2 weeks before actual conception occurs.