There will be a mild increase in body temperature when you are about to have your period. There are several reasons for this: First, during the first few days of a woman’s period, the hormone levels in her body will change significantly, such as estrogen, progesterone, luteinizing hormone, follicle stimulating hormone, and thyroid hormone, all of which will rise, increasing the metabolism of substances and leading to an increase in body temperature. Secondly, the biological clock of a woman will change when she is about to have her period, which can lead to a short period of temperature rise, which is not obvious and is a normal physiological phenomenon, so there is no need to worry. Third, the nervous system tension and excitability will increase when the menstruation is approaching, which can indirectly lead to an increase in body temperature.