System and method for determining temperature nadir of a female

1. An electronic system for determining a temperature nadir during a menstrual cycle of a female human, the system comprising:

a wearable device including a first sensor system configured to be worn in contact with skin of the female human and to determine a temperature of the female human, and

a processor configured to receive the temperature of the female human from the first sensor system and one or more further measured physiological parameters of the female human in a current menstrual cycle, wherein the one or more further measured physiological parameters of the female human comprise at least one of: heart rate or heart rate variability;

the processor being further configured to determine a detected starting point of a fertility phase of the female human in the current menstrual cycle based at least in part on a change in the one or more further measured physiological parameters of the female human, wherein the detected starting point of the fertility phase is determined based on:

(i) a defined length of time after a duration of an interval between pulses of the heart rate exceeds a defined threshold value during the current menstrual cycle, or

(ii) when the duration of the interval between pulses of the heart rate drops below the defined threshold value after the duration of the interval between pulses of the heart rate previously exceeded the defined threshold value during the current menstrual cycle; and

the processor being further configured to, after the detected starting point of the fertility phase, detect the temperature nadir as a temporary decrease in the temperature received from the first sensor system, wherein the processor is configured to detect the temperature nadir in a time window after the detected starting point of the fertility phase of the female human in the current menstrual cycle, a time of the temperature nadir being indicative of time of ovulation and peak oestrogen level.

2. The electronic system of claim 1 , wherein the processor is configured to determine the nadir of the temperature by detecting the temporary decrease of the temperature within a time window around a probable time when the ovulation or peak oestrogen level is expected to occur, the probable time being based on the detected starting point of the fertility phase of the female human.

3. The electronic system of claim 2 , wherein the processor is configured to determine the probable time when the ovulation or peak oestrogen level is expected to occur as a first time-probability distribution, indicating for various points in time of the time window the probability of the ovulation or peak oestrogen level to occur, and to determine a second time-probability distribution, indicating for various points in time of the time window the probability of the nadir of the temperature to occur, by detecting the temporary decrease of the temperature, and to determine the time of the temperature nadir by comparing a combination of the first time-probability distribution and the second time-probability distribution to a threshold.

4. The electronic system of claim 2 , wherein the processor is configured to determine the probable time when the ovulation or peak oestrogen level is expected to occur by adding a probable time duration to the detected starting point of the fertility phase.

5. The electronic system of claim 2 , wherein the electronic system further comprises a data store, and the processor is configured to store in the data store at least one of: one or more further physiological parameters measured by a second sensor system, included in the wearable device and configured to be worn in contact with the skin of the female human, and other external indicators related to the female human, and to determine the probable time when the ovulation or peak oestrogen level is expected to occur, using the one or more further physiological parameters and other external indicators of the female human stored during a plurality of menstrual cycles.

6. The electronic system of claim 1 , wherein the wearable device includes a second sensor system configured to be worn in contact with the skin of the female human and to determine a heart rate of the female human; and the processor is configured to determine a change in pulse during a menstrual cycle using the heart rate, and wherein the determination of the detected starting point of the fertility phase is based at least in part on the change in the pulse.

7. The electronic system of claim 6 , wherein the processor is configured to determine the detected starting point of the fertility phase using the time (t 1 ) of the change of the pulse from a comparatively short interval between heartbeats to a comparatively longer interval between heartbeats.

8. The electronic system of claim 6 , wherein the processor is configured to determine the detected starting point of the fertility phase by detecting a time indicative of an end point of a period of pulses with a comparatively long interval between heartbeats.

9. The electronic system of claim 1 , wherein the wearable device includes a second sensor system configured to be worn in contact with the skin of the female human and to determine a heart rate variability of the female human; and the processor is configured to determine the detected starting point of the fertility phase, using a time of increased heart rate variability.

10. The electronic system of claim 9 , wherein the second sensor system is configured to determine acceleration of the female human; and the processor is configured to detect during menstrual cycles sleep phases with resting pulse using the heart rate variability and the acceleration, to determine a change in the resting pulse during a menstrual cycle using the heart rate, and to determine the detected starting point of the fertility phase, using a time of the change in the resting pulse.

11. The electronic system of claim 1 , wherein the wearable device includes a second sensor system configured to be worn in contact with the skin of the female human and to determine one or more further physiological parameters of the female human; and the processor is configured to determine correlations of at least one of: the one or more further physiological parameters measured by the second sensor system and other external indicators related to the female human, and to determine the detected starting point of the fertility phase, using a correlation time of the correlations of the one or more further physiological parameters and other external indicators.

12. The electronic system of claim 1 , wherein the processor is arranged in the wearable device and configured to determine the time of the temperature nadir using physiological parameters measured by the sensor systems of the wearable device.

13. The electronic system of claim 1 , wherein the processor is arranged in an external system, separated from the wearable device, the wearable device further comprises a communication module configured to transmit physiological parameters measured by the sensor systems of the wearable device to the external system, and the processor is configured to determine the time of the temperature nadir using the physiological parameters received from the wearable device.

14. A method of determining a temperature nadir during a menstrual cycle of a female human, the method comprising:

receiving in a processor from a first sensor system of a wearable device a temperature of the female human;

receiving in the processor one or more further measured physiological parameters of the female human in a current menstrual cycle, wherein the one or more further measured physiological parameters of the female human comprise at least one of: heart rate or heart rate variability;

determining by the processor a detected starting point of a fertility phase of the female human in the current menstrual cycle based at least in part on a change in the one or more further measured physiological parameters of the female human, wherein the detected starting point of the fertility phase is determined based on:

(i) a defined length of time after a duration of an interval between pulses of the heart rate exceeds a defined threshold value during the current menstrual cycle, or

(ii) when the duration of the interval between pulses of the heart rate drops below the defined threshold value after the duration of the interval between pulses of the heart rate previously exceeded the defined threshold value during the current menstrual cycle; and

after the detected starting point of the fertility phase, detecting by the processor the temperature nadir as a temporary decrease in the temperature received from the first sensor system, wherein the temperature nadir is detected in a time window after the detected starting point of the fertility phase of the female human in the current menstrual cycle, a time of the temperature nadir being indicative of time of ovulation and peak oestrogen level.

15. The method of claim 14 , wherein the method further comprises determining by the processor a probable time when the ovulation or peak oestrogen level is expected to occur as a first time-probability distribution, indicating for various points in time of the time window the probability of the ovulation or peak oestrogen level to occur; and determining by the processor a second time-probability distribution, indicating for various points in time of the time window the probability of the nadir of the temperature to occur, by detecting the temporary decrease of the temperature; and determining by the processor the time of the temperature nadir by comparing a combination of the first time-probability distribution and the second time-probability distribution to a threshold.

16. A computer program product comprising a non-transient computer readable medium having stored thereon computer program code configured to control one or more processors of a computerized system, such that the computerized system performs the steps of:

receiving from a first sensor system of a wearable device a temperature of a female human;

receiving one or more further measured physiological parameters of the female human in a current menstrual cycle, wherein the one or more further measured physiological parameters of the female human comprise at least one of: heart rate or heart rate variability;

determining a detected starting point of a fertility phase of the female human in the current menstrual cycle based at least in part on a change in the one or more further measured physiological parameters of the female human, wherein the detected starting point of the fertility phase is determined based on:

(i) a defined length of time after a duration of an interval between pulses of the heart rate exceeds a defined threshold value during the current menstrual cycle, or

(ii) when the duration of the interval between pulses of the heart rate drops below the defined threshold value after the duration of the interval between pulses of the heart rate previously exceeded the defined threshold value during the current menstrual cycle; and

after the detected starting point of the fertility phase, detecting a temperature nadir as a temporary decrease in the temperature received from the first sensor system wherein the temperature nadir is detected in a time window after the detected starting point of the fertility phase of the female human in the current menstrual cycle, a time of the temperature nadir being indicative of time of ovulation and peak oestrogen level.