Basal Body Temperature (BBT), also known as resting body temperature, is the temperature taken after 6-8 hours of sleep, for example, in the morning when a woman wakes up from a deep sleep and her body temperature has not been affected by exercise, diet or emotional changes. Basal body temperature is the easiest and most practical way to help us understand ovarian function. It requires long-term adherence, and generally requires more than 3 consecutive menstrual cycles to indicate the problem, allowing the doctor to have a more comprehensive understanding of the condition and can help you with more targeted treatment to achieve the best results. The mechanism of basal body temperature change The body temperature regulation center is extremely sensitive to the action of progesterone (also known as luteinizing hormone), and a certain amount of progesterone (12.8nmol/L) can cause a rise in body temperature. On the day after ovulation, the corpus luteum is formed and the luteum secretes progesterone, which causes the body temperature to rise by 0.3-0.5 degrees Celsius, resulting in high and low body temperature changes, with the high temperature period lasting about 14±2 days. If there is no pregnancy, the corpus luteum atrophies and stops producing progesterone, the body temperature drops back to the basic line and menstruation comes. If you are pregnant, the corpus luteum is supported by the hormones secreted by the embryo and continues to secrete progesterone, and the body temperature continues to be high. If the ovaries are malfunctioning and there is no ovulation or corpus luteum formation, the body temperature will continue to be low. How to measure and record basal body temperature 1) First, prepare an ordinary mercury thermometer and clean it. 2) Every day before going to bed, dump the thermometer and put it on the side of your pillow. 3）Wake up in the morning, do not move or talk, gently reach out and pick up the thermometer, put it in your mouth or under your tongue, and measure it for 5 minutes. 4) After waking up, record the temperature in the following format: The role of basal body temperature 1, to determine whether ovulation guidance contraception General follicular phase basal body temperature of 36.5 ℃, luteal phase rise of 0.5 ℃ or more, and thus the appearance of biphasic performance, indicating ovulation, if the monophasic type without late rise in the temperature curve, suggesting no ovulation, its accuracy rate of 70% to 80%. If the body temperature increases by 0.3 to 0.6°C or even more within 24 hours, then it indicates ovulation. In addition, the basal body temperature is also a good indicator of the quality of the ovum. If the basal body temperature is high for a long period of time, lasting 13 to 14 days, then the quality of the eggs is good. 2. Diagnose early pregnancy and determine early pregnancy status If the basal body temperature is high for more than two weeks, you should consider going to the hospital for a check-up because you may be pregnant. Early pregnancy can be determined if it is ≥20 days. A gradual decrease of BBT curve in early pregnancy indicates luteal insufficiency or placental malfunction and a tendency to miscarriage. 3.Observation of luteal function BBT should rise immediately after ovulation and continue at a high level for ≥11 days. If BBT rises in a stepped pattern, the curve takes 3 days to reach a high level or BBT rises steadily for <11 days, luteal phase defeot (LPD) can be diagnosed. 4, suggesting other pathologies BBT does not decrease during menstruation and may have endometriosis or early subclinical miscarriage, as the foci of endometriosis produce absorption heat after bleeding. Uterine amenorrhea, such as endometrial adhesions, should be considered when the BBT is biphasic in patients with primary amenorrhea. 5. Projecting the appropriate time for endometrial biopsy Patients with irregular cycles, to understand whether there is a secretory response in the endometrium and the function of the corpus luteum, endometrial biopsy should be performed 2 to 3 days before the estimated next menstrual flow after the rise of BBT.