There is no absolute safe period for women, and there is no concept of safe period in medicine. Many people believe that the safe period in the menstrual period before 5 days and 4 days after the end of menstruation, when the woman is not in the ovulation, and the end of menstruation after the end of the uterine lining is thin, the fertilized egg is not easy to bed development. But in fact, there is no absolute safe period for women, the time of ovulation is affected by many factors, no matter when, sex should be good contraceptive measures to prevent unwanted pregnancy. Female ovulation time is susceptible to the external environment, emotional changes, lifestyle habits and other factors affect the delay or advance, or even additional ovulation, if there is a requirement for fertility, increase the number of coitus during the ovulation period can improve the chances of pregnancy. If you do not want to have children, you should pay attention to contraception to prevent unwanted pregnancy.