Menstrual cycle tracking

A system for detecting a menstrual cycle onset, comprising:

• a wearable ring device configured to be worn on a finger of a user, wherein the wearable ring device comprises one or more temperature sensors configured to interface with a skin surface of the finger of the user to measure distal temperature data continuously for at least a plurality of days;
• a user device communicatively coupled to the wearable ring device and comprising a graphical user interface;
• and
• one or more processors coupled to the wearable ring device, the user device, or both, the one or more processors configured to:
• cause the graphical user interface of the user device to display a request to activate a menstrual cycle tracking mode of a health-related application;
• receive, in response to the request, a first user input indicating activation of the menstrual cycle tracking mode;
• receive, from the wearable ring device, physiological data measured from the user by the wearable ring device, the physiological data comprising the distal temperature data and heart rate data;
• filter out at least a first portion of the distal temperature data corresponding to a time interval for which the heart rate data satisfies a threshold;
• fit a second portion of the distal temperature data measured for at least the plurality of days to a trigonometric or polynomial function comprising a plurality of features based at least in part on filtering out at least the first portion of the distal temperature data, wherein the second portion of the distal temperature data excludes the first portion of the distal temperature data based at least in part on the filtering;
• calculate a duration between the plurality of features and the corresponding plurality of menstrual cycle onset days based at least in part on fitting the second portion of the distal temperature data to the trigonometric or polynomial function;
• estimate a range of first future menstrual cycle onset days based at least in part on applying the duration to a most recent feature of the trigonometric or polynomial function;
• and
• cause the graphical user interface of the user device to display a user interface page of the health-related application, the user interface page comprising an indication of the range of first future menstrual cycle onset days.