If the patient has had regular periods in the past, the safe period is 5 days after the menstrual period clears or 7 days before the menstrual period. However, the safe period is only relatively safe, not absolutely safe from pregnancy. The safe period is divided into pre-ovulatory and post-ovulatory safe periods. The 5 days just after menstruation is considered the safe period before ovulation, and the 7 days from the end of ovulation to the next menstrual period is the post-ovulatory safe period, i.e. the week before the menstrual period belongs to the post-ovulatory safe period. In addition, there are a few women who have intercourse during the safe period also have the possibility of pregnancy, such as ovulation twice a month, or irregular menstrual cycles that lead to irregular ovulation, so they may still conceive during the safe period. So if a woman is not ready to get pregnant, it is best to take effective contraception during the safe period to avoid unwanted pregnancy.