It is also possible to get pregnant by having intercourse before or after menstruation. Although theoretically, before or after menstruation is a safe period and you should not get pregnant, the safe period and the ovulation period are relative. Changes in the environment, mood changes, and psychological stress and anxiety can all lead to changes in the safe period and ovulation. If you have intercourse at the time of ovulation, but ovulation is pushed back and mistaken for a safe period around the time of menstruation, you may become pregnant. Theoretically, as long as the sperm enters the vagina there is a possibility of pregnancy, it is just that the chances of getting pregnant during the safe period are low and the chances of getting pregnant during ovulation are high. Therefore, if there is no requirement for childbearing, sexual life is to bring tools to prevent pregnancy or contraception with an IUD.