Frequently asked questions about the cycle and ovulation
On what day does ovulation happen?
Not necessarily on day 14: in a study of more than 600,000 cycles tracked by an app, the cycle lasted 29.3 days on average and the phase before ovulation 16.9 days, with wide differences from one woman to another. Only 13% of cycles lasted 28 days (Bull, 2019).
How many days does the fertile window last?
About 6 days: the 5 days before ovulation and the day of ovulation. The chances are highest on the last 2 days before ovulation (Wilcox, 1995).
Why does body temperature rise after ovulation?
Because of progesterone, which rises after ovulation: waking temperature goes up by about 0.3 to 0.5 °C (0.5 to 1 °F) and stays higher until the period (StatPearls). This rise confirms ovulation after the fact but cannot predict it.
Why are you hungrier before your period?
In the second half of the cycle, women eat a little more on average: about 170 kcal more per day according to a review of 15 groups of women (330 in total), with fairly mixed studies (Tucker, 2025). Progesterone might stimulate appetite, but this is not proven.