Abstract: The present invention relates to a system for measuring an oral temperature of a female subject during an ovulation cycle of the female subject for assisting the female subject in determining the next ovulation cycle for fertility and/or birth-control and includes a method and apparatus for predicting a commencement of a new ovulation cycle in a female subject including measuring and communicating the data to a remote computing platform by daily measuring the oral temperatures and calculating an average oral temperature for an ovulation cycle. The daily oral temperature measurements and/or average oral temperatures are also available on external databases and may be used for comparing and checking the current temperature measurements. Different sensors are available for other purposes.