Generally the day before your period without contraception, the probability is that you will not get pregnant. A woman’s menstrual cycle lasts 28-35 days, and the 14 days before a woman’s period is the day of ovulation, and the 5 days before and after is the period of ovulation. On the day before menstruation, there is usually no ovulation, so the chances of pregnancy are very low, even without contraception, usually not pregnant. However, there is no 100% clinical contraception, and if faced with irregular periods, the time of ovulation can be uncertain, so even during the theoretical safe period, ovulation may still occur. If there is any discomfort or other problems during menstruation, it is recommended to go to the hospital in time for examination, to clarify the cause of the disease and then follow the doctor’s instructions to deal with the treatment.