The first seven days and the last eight days of menstruation are relatively safe periods, but they are not absolutely risk-free. Women should understand their menstrual cycles, grasp the regularity of ovulation, and take appropriate contraceptive measures. Even within the safe period, the possibility of pregnancy cannot be completely ruled out. Therefore, for women who want to avoid pregnancy, the best thing to do is to use reliable contraceptive methods, such as condoms or medical contraception, to ensure safe and effective prevention of unwanted pregnancy.