Unobtrusive ovulation tracking system and method using a subject's heart rate

1. A system for unobtrusive ovulation tracking, comprising:

a sensor for obtaining a heart signal;

a processing unit configured to process the heart signal; and

an evaluation unit configured to analyze the heart signal to predict likelihood of ovulation, wherein the processing unit is configured to extract heart rate variability features from the heart signal, and wherein the evaluation unit is further configured to predict likelihood of ovulation by correlating absolute measures of the heart rate variability features to estrogen levels.

2. The system according to claim 1 , wherein the evaluation unit comprises a phased locked loop which locks onto the heart rate variability features to predict likelihood of ovulation.

3. The system according to claim 1 , further comprising an activity determination unit configured to provide an activity indicator indicative of a current activity level and/or a user's physical condition, in particular a circadian rhythm or phase of the subject, wherein the evaluation unit is further configured to predict the likelihood of ovulation based on said activity indicator.

4. The system according to claim 3 , further comprising a motion sensor configured to determine motion and/or orientation data of the subject, wherein the activity determination unit is configured to provide the activity indicator based on said motion and/or orientation data.

5. The system according to claim 3 , further comprising an ambient sensor configured to determine an ambient temperature and/or ambient light levels, wherein the activity determination unit is configured to provide the activity indicator based on said ambient temperature and/or ambient light levels.

6. The system according to claim 3 , further comprising a calendar unit configured to track local date and time information, wherein the activity determination unit is configured to provide the activity indicator based on said local date and time information.

7. The system according to claim 1 , further comprising a data integration unit configured to integrate testing results from other fertility tracking devices, in particular luteinizing hormone testing devices and/or basal body temperature thermometers, wherein the evaluation unit is further configured to predict the likelihood of ovulation based on the heart signal and/or the testing results from other fertility tracking devices.

8. The system according to claim 1 , further comprising a data storage for archiving the heart signal, wherein the evaluation unit is further configured to predict the likelihood of ovulation based on a current and an archived heart signal.

9. The system according to claim 1 , further comprising a communication unit for exchanging data with external sensors and/or processing units and/or user input, wherein the evaluation unit is further configured to predict the likelihood of ovulation based on said data.

10. The system according to claim 1 , further comprising a training unit configured to adjust the evaluation unit based on training data and/or individual user input.

11. The system according to claim 1 , wherein the sensor is an optical heart rate sensor such as a photoplethysmography sensor.

12. The system according to claim 1 , wherein the sensor is a body-worn sensor.

13. The system according to claim 1 , wherein the sensor is detached from the subject, in particular a camera and/or a biofeedback device.

14. A method for unobtrusive fertility tracking, comprising the steps of:

receiving a heart signal from a sensor;

processing the heart signal; and

analyzing the heart signal to predict likelihood of ovulation,

wherein the method further comprises the steps of:

extracting heart rate variability features from the heart signal; and

predicting likelihood of ovulation by correlating absolute measures of the heart rate variability features to estrogen levels.

15. A non-transitory computer readable medium comprising a computer program comprising program code encoded on the computer readable medium, the program code for causing a processor to carry out the following steps:

receiving a heart signal from a sensor;

processing the heart signal;

analyzing the heart signal to predict likelihood of ovulation, including:

extracting heart rate variability features from the heart signal; and

predicting likelihood of ovulation by correlating absolute measures of the heart rate variability features to estrogen levels.

16. The method according to claim 14 , further comprising providing an activity indicator indicative of a current activity level and/or a user's physical condition, in particular a circadian rhythm or phase of the subject, the prediction based on said activity indicator.

17. The method according to claim 16 , further comprising determining motion and/or orientation data of the subject, the activity indicator based on said motion and/or orientation data.

18. The method according to claim 16 , further comprising determining an ambient temperature and/or ambient light levels, the activity indicator based on said ambient temperature and/or ambient light levels.

19. The method according to claim 16 , further comprising tracking local date and time information, the activity indicator based on said local date and time information.

20. The method according to claim 14 , further comprising integrating testing results from other fertility tracking devices, in particular luteinizing hormone testing devices and/or basal body temperature thermometers, the likelihood of ovulation predicted based on the heart signal and/or the testing results from other fertility tracking devices.