When Did Conception Occur?
Conception (fertilization) typically occurs about 14 days after the first day of your last period, assuming a 28-day cycle. Sperm can survive in the reproductive tract for up to 5 days, so the conception window is actually several days wide.
Conception vs Gestational Age
Gestational age (used by doctors) counts from LMP. Conceptional age (embryonic age) counts from actual conception, about 2 weeks later. A baby that's 8 weeks gestational age is 6 weeks from conception.
Why Conception Date Matters
Knowing conception date helps estimate paternity window, understand early pregnancy events, and calculate more accurate due dates if LMP is unknown or cycles are irregular. However, it's always an estimate with a range of several days.
Quick Tips
- BMI alone doesn't reflect overall health
- TDEE varies based on activity level
- Consult a healthcare professional for medical decisions
Frequently Asked Questions
No, only an estimate. Sperm can survive up to 5 days, making the window about 3-7 days.
They're close but not identical. Conception occurs within 24 hours of ovulation.
Assumes ovulation on day 14 of a 28-day cycle. Actual ovulation varies.
Early ultrasound (6-12 weeks) gives accurate gestational age, from which conception is estimated.
It narrows the window but doesn't definitively establish paternity. DNA testing is needed.