A few days after the menstrual period ends is the dangerous period.

The dangerous period of the menstrual cycle, also known as the ovulation period, generally refers to the time during a woman's menstrual cycle when pregnancy is most likely. In a standard 28-day menstrual cycle, ovulation usually occurs around the 14th day after the start of menstruation. However, this is only an estimate, and the actual day of ovulation may vary from person to person and can be influenced by multiple factors. To determine the dangerous period more accurately, it is necessary to calculate the length of the menstrual cycle and identify one's own ovulation day. Ovulation typically occurs about 14 days before the start of the next menstrual period. For example, if the cycle is 28 days long, ovulation would occur approximately on day 14, and the fertile window would be roughly from five days before ovulation to one day after, that is, from day 9 to day 18 of the menstrual cycle. However, this method is not sufficiently accurate for women with irregular cycles or cycles of different lengths. If one wishes to avoid unintended pregnancy, it is best to use more reliable contraceptive methods, such as birth control pills, condoms, or consult a doctor regarding other contraceptive options.