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Understanding the Fertile Window

The fertile window typically spans 6 days each cycle: the 5 days before ovulation and ovulation day itself. This is because sperm can survive in the female reproductive tract for up to 5 days, while the egg survives only 12–24 hours after release. The highest probability of conception occurs with intercourse 1–2 days before ovulation.

World Health Organization (WHO) – Family Planning

Factors That Affect Cycle Regularity

Menstrual cycle length can vary due to stress, weight changes, exercise habits, and underlying health conditions. The WHO notes that cycles between 21 and 35 days are considered normal. If your cycles vary significantly (more than 7–9 days month to month), calendar-based methods become less reliable and additional tracking methods may be helpful.

WHO – Reproductive Health Guidelines

When to Seek Medical Advice

Medical organizations worldwide generally recommend seeking fertility advice if you've been trying to conceive for 12 months without success (or 6 months if you're over 35). Other reasons to consult earlier include very irregular or absent periods, a history of pelvic infections, or known reproductive health conditions.

International Federation of Gynecology and Obstetrics (FIGO)

🌸 Eisprung

Tritt typischerweise 12-16 Tage vor Ihrer nächsten Periode auf, unabhängig von der Zykluslänge.

⏰ Fruchtbares Fenster

Der 6-Tage-Zeitraum, der am Eisprungtag endet, in dem eine Empfängnis möglich ist.

💯 Bester Zeitpunkt

Geschlechtsverkehr 1-2 Tage vor dem Eisprung bietet die höchsten Empfängnischancen.

How is ovulation day calculated?

Ovulation typically occurs 12–16 days before your next period starts, with 14 days being the average. This calculator estimates ovulation by subtracting 14 days (or your luteal phase length if known) from your expected next period date. For women with a 28-day cycle, ovulation usually occurs around day 14; for a 32-day cycle, around day 18.

Can I get pregnant outside my fertile window?

Conception is highly unlikely outside the fertile window. The egg survives only 12–24 hours after ovulation, and sperm typically survive 3–5 days in the reproductive tract. However, cycle predictions are estimates—ovulation can shift due to stress, illness, or hormonal changes. If avoiding pregnancy, calendar methods alone have a typical-use failure rate of around 12–24%.

What can I do to improve my chances of conceiving?

Evidence-based recommendations include: having intercourse every 1–2 days during your fertile window, maintaining a healthy weight, taking folic acid supplements, limiting alcohol and caffeine, not smoking, and managing stress. Most healthy couples conceive within 12 months of regular trying. Tracking your cycle helps identify your personal fertile window.