Apparatus and methods are described for monitoring a female subject. A sensor is configured to monitor the subject without contacting the subject or clothes the subject is wearing, and without viewing the subject or clothes the subject is wearing, and to generate a sensor signal in response to the monitoring. A computer processor is configured to receive the sensor signal, and to analyze the sensor signal. In response to the analyzing, the computer processor is configured to automatically identify a menstrual state of the subject, and to generate an output in response thereto. Other applications are also described.