The basal body temperature of the menstrual cycle with ovulation will show “characteristic” changes, and the basal body temperature can be measured to know whether ovulation. How to measure: Prepare a mercury thermometer and shake the mercury column of the thermometer to below 35 degrees every night before going to bed. Immediately after waking up each morning, place the thermometer under the tongue and try not to move, take the thermometer reading after 5 minutes and record it on a special form. It is strictly forbidden to get up, brush teeth, urinate or defecate, eat or talk before taking the temperature. The day of menstruation, vaginal bleeding, and intercourse are marked on.