Question 1

How is the conception date estimated?

Accepted Answer

Conception typically occurs about 14 days after the first day of the last menstrual period (around ovulation). From a due date, we subtract 266 days (38 weeks of gestation) to estimate conception.

Question 2

How accurate is this estimate?

Accepted Answer

This is an approximation based on a 28-day cycle. Actual conception can vary by several days depending on ovulation timing, cycle length, and sperm viability (up to 5 days). Ultrasound dating is more precise.

Question 3

What is the difference between gestational age and fetal age?

Accepted Answer

Gestational age is counted from the LMP (about 2 weeks before conception). Fetal age counts from actual conception and is about 2 weeks less than gestational age.

Milestone	Date
Last Menstrual Period	Monday, September 8, 2025
Estimated Conception	Monday, September 22, 2025
Estimated Due Date	Monday, June 15, 2026
Conception Window	Friday, September 19, 2025 to Thursday, September 25, 2025
1st Trimester Ends	Monday, December 1, 2025
2nd Trimester Ends	Monday, March 16, 2026

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