The day when the basal body temperature drops to the lowest during temperature monitoring is the day of ovulation. On the day of ovulation, the body temperature drops to the lowest due to the decrease of estrogen and progesterone in the body. After ovulation, the basal body temperature will rise again under the effect of progesterone, it will be about 0.5℃ higher than the day of ovulation, the basal body temperature will be above 36.8℃ and below 37.5℃, which is a normal physiological phenomenon, and this high temperature state will last for more than 12 days clinically if there is no pregnancy. If you are pregnant, this high temperature will last for more than 15 days, indicating the possibility of pregnancy, and you can use the morning urine to do an early pregnancy test to find out if you are pregnant. In addition, if you plan to get pregnant, choosing to have intercourse on the day when the basal body temperature is at its lowest will increase the chances of pregnancy.