Basal Body Temperature (BBT) is the body temperature of the human body in the resting state, usually measured in the morning after waking up and not affected by exercise, diet and emotional changes (for night shift workers, the body temperature after 5-6 hours of continuous sleep can be measured as the basal body temperature). For those with regular menstrual cycle (about 28 days), ovulation usually occurs in the middle of menstruation – about 14 days before the next menstrual period; the basal body temperature is often low in the first half of the menstrual cycle, i.e. before ovulation, about 36.5℃; the body temperature drops slightly during ovulation and rises about 0.3-0.5℃ after ovulation, and continues until the beginning of the menstrual period It continues to decrease until the menstrual period. Therefore, observing the change of basal body temperature can help to understand the function of ovaries, whether ovulation, pregnancy, signs of miscarriage, etc. Measurement methods and precautions: 1. Use an ordinary thermometer (oral table); 2. The day before going to sleep, put the thermometer (mercury column degree below 35 ℃), put it at the head of the bed, pillow (after waking up, take it with you), and prepare special recording paper and pen; 3. The next morning when you wake up (do not turn over, get up, go to the toilet, eat, talk, etc.), that is, put the thermometer under the tongue for 5 minutes, take it out and observe the temperature. The temperature of the thermometer is observed, and then the temperature is marked with a dot “●” on the special record sheet for basal body temperature, and the dots are connected together, which becomes the basal body temperature curve; 4, special markings: the onset of menstruation can be marked with an X, the amount of different sizes of X markings are available; the day of intercourse is marked with “▲ “5. insist on measuring at least 3 menstrual cycles; bring the basal body temperature measurement record to the attending doctor for analysis. Note: Since it is not guaranteed that you wake up at the same time and in the same state every day, the measured BBT increase often lags behind the ovulation day (the temperature may increase many days after ovulation), so the ovulation day measured here is for reference only.