Level 1: What is the safety period? The safe period refers to the period of time in a woman\’s menstrual cycle when she is least likely to become pregnant. During this time, a woman’s ovulation period has passed and her eggs have died or are immature, thus avoiding the possibility of pregnancy. Level 2: How to calculate the safety period? Calculating the safe period requires knowing the length of a woman\’s menstrual cycle and when she ovulates. Generally speaking, the menstrual cycle is 28 days, and the ovulation time is about 14 days before the start of menstruation. Therefore, in a 28-day cycle, days 8 to 19 are