Understanding the Fertile Window and Ovulation
How to identify your fertile window accurately and why standard 28-day assumptions may not match your biology.
Reviewed by Dr. Sushmitha, MBBS, MS (OBG)
October 2026 · Evidence-Based Healthcare
Conception can only occur during a specific, brief biological window each menstrual cycle — known as the fertile window.
The fertile window spans approximately six days: the five days leading up to ovulation and the day of ovulation itself. This is because healthy sperm can survive in the female reproductive tract for up to 5 days, whereas an ovulated egg remains viable for only 12 to 24 hours.
While textbooks often describe ovulation as occurring on Day 14 of a 28-day cycle, menstrual cycles vary widely between women. If your cycle is 32 days, ovulation typically occurs around Day 18. If your cycle is 25 days, ovulation may happen around Day 11.
Methods for tracking ovulation include monitoring cervical mucus changes, using home urinary luteinizing hormone (LH) detection kits, and in clinical practice, transvaginal follicular tracking scans.
For couples trying to conceive, having intercourse every 1 to 2 days during the fertile window ensures optimal sperm availability when the egg is released.
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Frequently Asked Questions
Follicular tracking is a series of brief ultrasound scans performed between Day 9 and Day 16 of the menstrual cycle to accurately measure growing follicles and confirm exact ovulation timing.