Abstract: 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.