The number of days varies based on the woman's cycle length. The average number of days a woman would be considered fertile and would need to abstain from sex or use another method varies between 12 to 18 days dependent on the natural family planning tracking methodology. To avoid an unintended pregnancy, you must use another contraceptive method, such as condoms, during your fertile days.
Yes - during monthly bleeding the chances of pregnancy are low but not zero. Bleeding itself does not prevent pregnancy. In the first days of monthly bleeding, the chances of pregnancy are the lowest. As the days pass, the chances of pregnancy increase, whether or not you are still bleeding. The risk of pregnancy rises until ovulation. The day after ovulation the chances of pregnancy begin to drop steadily. Some natural family planning methods that depend on cervical secretions advise avoiding unprotected sex during monthly bleeding because cervical secretions cannot be detected during bleeding and there is a small risk of ovulation at this time.
Ovulation varies depending on the length of your menstrual cycle, which can range from 21 days up to 35 days.
Let’s have a look at two examples:
Ovulation happens about 14 days before your menstruation starts. That means:
If your average menstrual cycle for example is 28 days, you ovulate around day 14, and your most fertile days would generally be 12, 13 and 14.
If your average menstrual cycle is 35 days ovulation happens around day 21 and your most fertile days would generally be 19, 20 and 21. How to count your cycle? The first day of your menstruation is the beginning of a new cycle, hence day 1.
If you do not want to become pregnant, using contraception also on the other days of your cycle is very important because chances of pregnancy may be lower but not zero. Because the lifespan of sperm is unpredictable and can last up to 5 days, unprotected sex can lead to pregnancy from the first day of your menstruation.
PP-UN-WHC-GB-0084 September 2023