The safe period contraception method, also known as the natural contraceptive method, is based on the knowledge of female reproductive physiology to predict the date of ovulation and determine the fertile period of the cycle for abstinence to achieve the purpose of contraception. There are three main methods of contraception: 1, calendar method: for women with regular cycles, under normal circumstances, women’s menstrual cycle is about 28 days, ovulation day before and after 14 days before the next menstrual flow, so the day before and after ovulation is projected as the fertile period, the rest of the time is considered safe; 2, basal body temperature method: basal body temperature is the body temperature of healthy people when they wake up in the morning, it is generally the lowest temperature of the day. If the basal body temperature suddenly rises 0.3-0.5℃ on a certain day of the menstrual cycle, it is a sign of ovulation, and the basal body temperature is the lowest in the 24 hours before ovulation. However, the relationship between the curve of the basal body temperature and the time of ovulation is not constant, so it is not accurate. 3. Observe the changes of vaginal secretions: regulated by the hormones in the body, the temperature in the vagina changes regularly with the different periods of the menstrual cycle. Once a tendency to thin out the wet or sticky vaginal mucus is detected, it should be considered to be in the period of conception until the fourth day after the peak of thin, clear, stretchy mucus, when the alarm of the risk of conception is lifted. It is important to note that this method does not predict the time of ovulation, so it is best to use other contraceptive measures or avoid sexual intercourse between the first day of menstruation and the fourth day of peak mucus. It is best to use the above 3 methods of safe period contraception wisely, because the female menstrual cycle is easily disturbed by many factors, so the safe period is not absolutely safe, and couples using this method of contraception should be aware of this.