The safe period is around the 6th to 10th day and the 20th to 27th day of the menstrual cycle if menstruation is regular and lasts about 28 days, but there will be individual differences. For women with regular menstrual cycles, ovulation occurs about 14 days before the next menstrual period, and the 4-5 days before and after ovulation are the fertile period, and the rest of the time is the safe period. The safe period is the 6th to 10th day and the 20th to 27th day of the menstrual cycle if menstruation is regular for about 28 days after the 5th day of menstruation. However, since the time of ovulation is not absolutely reliable, there will be individual variations. For women who do not have childbearing requirements to use safe period contraception is not very reliable, it is recommended to use safe and reliable contraceptive measures under the guidance of a doctor, such as taking short-acting contraceptive pills, placing intrauterine devices, condoms, etc., in order to avoid the occurrence of unwanted pregnancies and increase the damage caused by abortion to the body.