Methods of detecting and predicting ovulation and a period of fertility include determining a series of measures indicative of the basal body temperature of a female human user to identify a temperature change event. The method includes obtaining, within a first 24 hour period, a plurality of first readings of the temperature of the female human user at intervals over a first extended period of at least an hour. The plurality of first readings are then processed to determine at least one first representative temperature reading representative of the basal body temperature of the user for the first extended period and the at least one first representative temperature reading is stored. The method is repeated for at least second and third 24 hour periods and the representative temperature readings are provided for analysis to identify a temperature change event for the female human user.
