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 person wakes up from a deep sleep and the body temperature has not been affected by exercise, diet or emotional changes. Basal body temperature is usually the lowest body temperature of the body during the day and night. The correct way to determine the basal body temperature 1, get a thermometer, master the meter reading method, to ensure accuracy. It is recommended to use a mercury thermometer. 2.Every night before going to bed, throw the mercury column of the thermometer to below 35 degrees and place it within reach after waking up. 3.Every morning immediately after waking up, put the thermometer under the tongue for 3-5 minutes and then take out the reading and record it on the special form. Do not measure under the armpit. Try to wake up at the same time every day to measure, if occasionally get up late and other circumstances need to be noted. 4.It is strictly forbidden to get up and put on clothes, urinate and defecate, drink, eat and talk before measuring body temperature. 5, should record whether there are many factors that affect the basic body temperature, such as: colds, insomnia, drinking alcohol, medication, emotions, etc.. In case of cold, fever, diarrhea, insomnia, alcohol consumption, use of electric blankets, excessive alcohol consumption, late sleeping and late waking, etc., often easily affect the basal body temperature, be careful when measuring, and at the same time pay attention to be specially marked instructions. 6, the onset of menstruation and intercourse day shall be marked with additional marks, menstrual flow crossed, intercourse circled. 7.Record the measurement results on the basal body temperature table, if you can not find the table can also be recorded on paper, preferably recorded in a special basal body temperature management tool, can be more convenient, intuitive view of the basal body temperature curve, at a glance to see the low temperature period and high temperature period. 8, please remember to bring the basal body temperature record form or paper head to the attending physician when you visit the clinic, as a reference for the diagnosis and treatment of diseases. The principle of basal body temperature The basal body temperature of normal women of childbearing age varies cyclically, and this temperature change is related to ovulation. The length of the menstrual cycle varies from person to person, ranging from 21 to 35 days, with an average of 28 days, separated by the day of ovulation, into the follicular phase before ovulation and the luteal phase after ovulation. The follicular phase is not necessarily long, but the luteal phase is fixed at about 12-14 days. On the day after ovulation, the corpus luteum forms in the ovary and secretes progesterone, causing the body temperature to rise by more than 0.3 degrees Celsius, resulting in a biphasic change in body temperature. The high temperature period lasts for about 12-14 days. 1.If there is no pregnancy, the corpus luteum atrophies and stops secreting progesterone, the body temperature drops and returns to the basic line, and menstruation comes. 2.If pregnant, the corpus luteum is supported by embryonic secretion of chorionic gonadotropin (hCG), which transforms into the corpus luteum of pregnancy and continues to secrete progesterone, and the body temperature continues to be high. 3, if the ovaries are not functioning well, there is no ovulation and no corpus luteum formation, the body temperature will continue to be low, the body temperature form into a monophasic, no biphasic curve changes. The role of basal body temperature 1, determine whether ovulation General follicular phase basal body temperature of 36.5 ℃ or less, luteal phase rise of 0.3 ℃ or more, and thus the appearance of biphasic performance, indicating ovulation, if the monophasic type without late rise in the temperature curve, suggesting that there is no ovulation, its accuracy rate of 70% to 80%. If the temperature increases by 0.3 to 0.5°C within 24 hours, then it indicates ovulation. In addition, the basal body temperature is also a good indicator of the quality of the ovulated eggs. 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. The basal body temperature usually rises with ovulation. During the first half of the menstrual cycle, the body temperature fluctuates below 36.6 degrees, and after ovulation, the body temperature rises in the second half of the menstrual cycle, fluctuating between 36.6 degrees and 37 degrees. If you are pregnant, your basal body temperature will not drop, but will remain high. If a higher basal body temperature persists for more than two weeks, consider going to the hospital for a checkup because you may be pregnant. If ≥ 16 days can be basically determined as early pregnancy. 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 insufficiency can be diagnosed. Correct recording of basal body temperature Correct recording of the measured basal body temperature on the temperature record sheet reflects the function of the ovaries. If it is not recorded correctly, it loses its meaning. The vertical axis coordinates in the chart indicate the degrees of body temperature, with each small cell being 0.1°C. The horizontal axis coordinates indicate the date and the day of the menstrual cycle, with each small cell being 1 day. Starting from the first day of menstruation, the measured temperature is plotted with dots in the corresponding temperature chart until the first day before the next menstruation, and then the dots are connected in order to form a basal body temperature curve for a menstrual cycle. Basal body temperature measurement The menstrual cycle is regular, with each cycle lasting 28 - 30 days. Ovulation usually occurs about 14 days before the next menstrual period, and the 7 days between 3 days before and 3 days after ovulation is the periovulatory period, which is also the fertile period. Of course, we often tell our patients that they do not need to look for the ovulation period intentionally (except in the case of couples who live apart and do not want to have intercourse during the ovulation period), there is always a chance to have intercourse 1-2 times a week. The 3-5 days around the ovulation period have a chance of pregnancy, not fixed on the day of ovulation. The other thing to note is that methods such as in vitro fertilization and ovulation calculation are not reliable, because a little semen will be spilled before ejaculation, and ovulation is often early or wrong. The safest method is to put on an IUD or condom (you need to put it on before intercourse, it may fail even before ejaculation). Basal body temperature is measured by: Taking your temperature with a mouth gauge every morning after waking up, preferably at the same time, without getting up. In general, the body temperature is always around 36.5 before ovulation. The body temperature drops slightly at ovulation. After ovulation it rises to about 37 degrees, with an average rise of about 0.5 degrees, and continues until the next menstrual period, when it returns to its original temperature level. If the basal body temperature is measured for three consecutive menstrual cycles, a more accurate ovulation date can be inferred. In normal times, the secretion of cervical mucus is influenced by the ovarian hormone cycle. In the pre-ovulatory period, the level of estrogen in the body increases, and the cervical mucus becomes thin, clear and transparent like egg white, and the amount increases. Therefore, during ovulation, sperm pass through the cervix most easily, and it is more difficult for sperm to pass through at other times. Does a biphasic basal body temperature necessarily mean that pregnancy is possible? It is clinically observed that about 13-44% of follicles develop abnormally in BBT biphasic patients by ultrasound monitoring and serum hormone level measurement (checked at ovulation and/or one week after ovulation). In contrast, abnormal follicular development and ovulation defects are found in about 83% of BBT biphasic infertility. Therefore, BBT biphasic cannot be used as the only criterion for ovulation, and ultrasound observation of follicular development and ovulation is of great clinical value. Where ultrasound indicates the disappearance of the main follicle during ovulation and the maximum main follicle diameter is ≥18 mm, it is generally considered as normal ovulation type and can lead to normal conception if there is no inflammation and no special conditions such as tubal lumen obstruction. In contrast, those with a maximum main follicle diameter of 15-18 mm and disappearance of the main follicle at the time of ultrasound suggestive of ovulation belong to the small follicle ovulation cycle, and the development, maturation and luteal function of such follicles are affected, which can easily lead to infertility. Follicles with normal development, whose diameter is more than 18 mm, and whose follicular growth curve before BBT rise is similar to normal cycle, but after BBT rise follicles continue to increase in size, with a diameter of more than 24-30 mm, shrinking or disappearing after menstruation, are mostly luteinized unruptured follicles (LUFS), i.e. the follicles are not expelled from the ovary after maturation, and of course the spermatozoa cannot unite.