A fertility indicator for measuring and detecting the body temperature of a human subject over a menstrual cycle having a timer for generating time based signals, and a logic circuit connected to the clock timer and being responsive to the time based signals for selecting the proper combinations of the time based signals and for indicating the correct present time. There is a temperature sensor coupled to the logic circuit for measuring the body temperature of the human subject. A solid state memory circuit having coded information command signals is coupled to the logic circuit for sequencing the logic circuit to take a plurality of temperature readings at a preset real time and to terminate the readings when the temperature has stabilized. A data storage circuit is provided for sequentially recording each of the stabilized temperatures that were measured, and a display circuit responsive to the solid state memory and data storage circuits, indicates the status of fertility of the subject during a menstrual cycle. There is also an alarm circuit coupled to the logic circuit and it has a variable pitch responsive to the solid state memory circuit for indicating the time when the subject's temperature has to be taken. Lights or words can indicate user's status.