Fertility Window

How the fertile window is computed

Ovulation occurs roughly 14 days before the next expected period — not 14 days after the last period (a common error). Sperm can survive in the cervix and fallopian tubes for up to 5 days; the released egg survives only 12–24 hours. The combined “fertile window” is therefore 5 days before ovulation, ovulation day itself, and 1 day after — about 6 days in total. Peak fertility is the 2–3 days before ovulation.

Worked example

A 28-year-old woman with a 30-day cycle whose last period started on 1 May 2026 expects her next period around 31 May. Ovulation ≈ 31 May minus 14 days = 17 May. Fertile window = 12 May to 18 May. Cycle irregularities (PCOS, thyroid issues, stress) shift the entire window — for a 35-day cycle, ovulation is around day 21 instead of day 14. Methods such as LH ovulation strips, basal body temperature charting, and cervical-mucus tracking refine the calendar estimate.

When to use this

• Couples trying to conceive naturally (TTC) and timing intercourse to the fertile window
• Tracking irregular cycles linked to PCOS or thyroid disorders — common in Indian women
• Pre-IVF planning — clinicians want a confirmed ovulation pattern
• Family-planning awareness — understanding when avoidance is needed (this is not a contraception method)

Related tools: ovulation tracker with body-temperature charting and pregnancy due-date calculator once conception is confirmed. Always consult a gynaecologist for medical advice.