The basal body temperature is checked when the woman wakes up without talking or drinking, and the temperature measured inside the mouth is recorded in a book. If the time of ovulation, that is, the high temperature phase can last for more than 14 days, it generally indicates pregnancy, because the progesterone level in a woman’s body is higher during ovulation, and progesterone can regulate the body temperature center to make the body temperature rise. If the rise in body temperature can be maintained for more than 14 days, it means that there has been the production of the corpus luteum of pregnancy. In normal women, if they are not pregnant, the body temperature will drop after 14 days when the level of hormones in the body drops significantly.