Abstract: The present invention teaches a device for monitoring periods of ovulation, which comprises a housing containing a thermometer that is introducible into the uterus. Temperature values are inputted into a memory at predetermined time intervals. Thus, for long periods of time, body temperature may be measured accurately and in constant intervals. In response to an external command signal, a transmitter and a receiver causes the stored temperature values to be retrieved. In this way, a complete chart of body temperature may be obtained in order to accurately determine a woman's ovulatory period, thereby allowing her to intentionally avoid or permit conception.