A method and apparatus for determining at least one representative temperature value for a female human user for an extended period includes receiving at least a first, a second and a third plurality of temperature measurements obtained from a female human user during at least first, second and third respective extended periods, wherein each extended period includes at least one hour and wherein the start of each extended period is separated by at least 8 hours. At least one representative temperature value is calculated for the second extended period. The representative temperature value is calculated using at least one first temperature value obtained from a plurality of measurements taken during the first extended period, at least one second temperature value obtained from a plurality of measurements taken during the second extended period and at least one third temperature value obtained from a plurality of measurements taken during the third extended period.