From the first day after menstruation to the first day of ovulation is the pre-safe period, which is about 7 days, and from the first day after ovulation to the first day of menstruation is the late safe period, which is about 8 days, and the total is about 15 days. Pregnant women can also calculate the safe period according to their personal ovulation period, and then remove the time other than the ovulation period, all belong to the safe period, ovulation refers to the 14th day before the menstrual flow, is the day of ovulation, the first 5 days of the day of ovulation, plus the last 4 days and the day of ovulation, a total of about 10 days is the ovulation period, so you can roughly calculate the specific time of the safe period.