The temperature curve is an easy and affordable way to determine the date of ovulation, in order to establish the period in which fertilization can take place and thus increase the chances of pregnancy. What is a temperature curve? The method of temperature curves, based on the research of Dr. Ogino and then Dr. Knaus, is based on physiological facts: body temperature changes during the menstrual cycle. In a normal menstrual cycle, with ovulation, the following variations are observed: During the first phase of the cycle, called follicular – from the first day of menstruation until ovulation, the temperature is relatively stable and usually below 37�C; Just before ovulation, it drops by a few tenths. This is the lowest point of the curve; After ovulation, the temperature rises by several tenths of a degree – on average 0.3 to 0.5 �C) and usually exceeds 37 �C. During the luteal phase, the temperature remains stable and forms a plateau. This increase is due to the secretion from the corpus luteum, formed from the remnants of the follicle ruptured during ovulation, of progesterone, some compounds of which have a hyperthermic effect. The corpus luteum is maintained throughout the luteal phase, which also determines the existence of a thermal plateau during this phase; In the absence of fertilization, the temperature returns to its normal level – below 37 �C, just before the onset of menstruation, which means the beginning of a new cycle; In pregnancy, the plateau continues even after the end of the cycle, because the corpus luteum continues its activity. Therefore, the normal temperature curve – in a menstrual cycle with ovulation is biphasic: It consists of two plateaus, separated by a small shift of a few tenths of a degree – 0.3 to 0.5 �C, which indicates that ovulation has occurred. Each plateau usually does not form a straight line, but rather a jagged curve, as the temperature can vary by 1 or 2 tenths from day to day. There is no “normal” core temperature. What matters is the occurrence of thermal displacement. Therefore, the temperature curve, also called the thermal curve method, allows to confirm the presence of ovulation and determine the date. It can be used to optimize the chances of getting pregnant by detecting the period when fertilization can take place or in case of infertility. In some cases it is also used as a method of natural contraception: this is the Ogino method. How to straighten the temperature curve? The method is as follows: Measuring the temperature every morning, before getting up, under the same conditions – with the same thermometer, using the same method: rectal, oral, measuring the temperature of the forehead and others. Then each day the temperature is recorded to the nearest tenth on a plain sheet of graph paper, on which the vertical axis indicates the temperature to the nearest tenth of a degree – 36 �C, 36.1 �C, 36.2 �C, 36, 3 �C, etc. On the horizontal axis is the day of the cycle – D1,corresponding to the first day of menstruation. The points are then connected day by day to get a curve. It is recommended to perform the temperature curve for at least two consecutive cycles. References: https://www.passeportsante.net/fr/grossesse/Fiche.aspx?doc=courbe-temperature-date-ovulation