Fertile days of a woman

In a 28-day menstrual cycle, which is the normal duration of a woman's cycle, ovulation takes place halfway through these days, that is, on day 14. This day and the immediately preceding and following this date are the most fertile days.

The first day of menstruation is the day when the following cycle starts, which means the beginning of the next menstrual cycle is determined by the date when menstruation starts.