A woman is typically fertile starting about 5 days before ovulation and up to 1 day after ovulation, with ovulation usually occurring around day 14 of an average 28-day menstrual cycle. Since the period marks the start of the cycle, fertility generally begins roughly 9 to 10 days after the start of the period in a typical cycle. However, if a woman has a shorter menstrual cycle or irregular cycles, ovulation and thus fertility can occur sooner after the period ends, making it possible to be fertile and get pregnant soon after the period, even within a few days after it ends. Sperm can survive inside the reproductive tract for up to 5 days, so intercourse towards the end of the period or just after can still result in pregnancy if ovulation occurs earlier than average. In summary:
- Fertile window is about 6 days: 5 days before ovulation plus ovulation day.
- For a regular 28-day cycle, ovulation (and fertile window) occurs around day 14.
- Fertility typically starts about 9 to 10 days after the period starts.
- In shorter or irregular cycles, fertility can start sooner after the period.
- Pregnancy soon after period is possible but less common in longer, regular cycles.
Therefore, fertility can begin approximately 5 to 10 days after the period starts, depending on cycle length and ovulation timing.
