1. An oral-based fertility monitoring system for insertion in the mouth and for monitoring fertility of a user, the system comprising: a clinical device, the clinical device comprising: a body adapted for comfortable insertion into the mouth of a patient; a first sensor located in the body, said first sensor adapted to measure temperature; a second sensor located in the body, the second sensor adapted to make a second measurement of the user; and a processor disposed within the body and being operable to receive a temperature signal and a second measurement signal from the temperature sensor and the second sensor respectively and to calculate a temperature value and a second measurement value of the user based on said received temperature signal and second measurement signal respectively; and said processor being further operable to determine a level of fertility based on at least said temperature value and said second measurement value.