How long after menstruation is dangerous period

The so-called dangerous period, in fact, refers to the female ovulation period, due to the expulsion of eggs at this time, so the same room does not take contraceptive measures easy to get pregnant, but because each woman's menstrual cycle, and menstrual cycle is different, so how long after menstruation is the dangerous period varies from person to person. However, if a woman's usual menstrual clean time takes 7 days, and the menstrual cycle is about 30 days, the normal 9-15 days after menstruation is a dangerous period.