TECHNICAL FIELD
[0001] The present invention generally relates to a system and method for determining female fertile window by measuring physiological parameters particularly the skin temperature and heart rate. The present invention, using a wearable device, accurately predicts the female fertility phase in female menstrual cycle by analyzing the skin temperature and heart rate recorded at regular time intervals.

BACKGROUND OF THE INVENTION

[0002] Fertility is the natural ability of male and female to produce off-springs. In females, the process of ovulation begins after attaining puberty usually at the age of 12-13 years. Studies report that a female’s fertility is at the peak in early and mid-20s to around 35 years of age, after which it starts to decline. Eventually, menopause marks the cessation of fertility.

[0003] Usually, the ovulation phase of a woman is predicted on the basis of basal body temperature, i.e. the lowest body temperature in a 24-hour period, and their menstrual cycle. Tracking fertile and infertile days of woman during their menstrual cycles helps them to avoid or encourage pregnancy.

[0004] Traditionally, the Fertility Awareness-based Methods (FAMs), also called the natural family methods or rhythm methods are the methods to track the ovulation-release of an egg to determine the fertility phase. Keeping the knowledge of the fertile days may help plan or prevent a pregnancy. The FAM methods typically comprise:

a) Calendar (rhythm) method: The method determines ovulation based on the occurrence of ovulation in past cycles;

b) Cervical mucus method: This method involves regular checking of the consistency (thickness) of the cervical mucus. The thickness of the vaginal discharge varies during different stages of the menstrual cycle. The mucus is usually more in quantity, wet and slippery (like raw egg-white) during the fertile period. During the non-fertile phase, quantity of mucus decreases and becomes sticky thereby preventing the sperm from entering the uterus. Therefore, the consistency of mucus is checked periodically to determine fertile and non-fertile phase.

c) Basal body temperature (BBT): The body temperature rises during the ovulation phase. Constant measuring the daily temperature first thing in the morning may determine the ovulation phase;

[0005] Billings Ovulation Method, the Creighton Model, and the Symptothermal Method are modern and more widely used FABMs and can be more narrowly defined as natural family planning.

[0006] The above methods are useful encompassing tracking of fertility window either by noting the information on papers or recording symptoms. However, the difficulty encountered in these methods is the high failure rate, difficulty in accurately predicting ovulation or fertile time. Moreover, these methods are cumbersome requiring commitment from both the partners in the sense that these methods depend both on careful, daily observation and charting of body signs, and on the cooperation of both partners in respecting fertile times.

[0007] WO 2016131630 A1discloses an electronic system for determining a fertility phase of a female human. The system detects sleep phases with resting pulse during menstrual cycles, 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 fertility phase using a time of the change in the resting pulse. However, WO 2016131630 A1 does not describe how to process the measured temperature data from device to obtain the fertility window. Further, the system is based on the change in heart rate variability value for fertility phase calculation.

[0008] Therefore, there is a need for a solution to make tracking and analyzing the physiological changes in basal body temperature of a woman easier and more accurate. The present invention provides a device and method to track the female fertility period on the basis of physiological data that includes temperature and heart rate.

SUMMARY OF THE INVENTION

[0009] The primary object of the present invention is to provide a device and method to predict the female fertility window accurately in a human female during menstrual cycle thereby improving the odds of conception by female.

[0010] Another object of the present invention is to determine or evaluate the female fertile window on the basis of physiological parameters specifically skin temperature, resting heart rate data.

[0011] Another object of the present invention is a device preferably wearable device comprising a temperature sensor in contact with the skin to measure the skin temperature.

[0012] Another object of the preset invention is a device comprising an optical sensor to measure the resting heart rate.

[0013] Yet another object of the present invention is to provide a device and method to track fertile window by processing the skin temperature, resting heart rate data collected for a particular user over a period of multiple menstrual cycles.

[0014] Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings, illustrations and examples to disclose the aspects of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The present invention will be better understood and its numerous objects, features, components and advantages are made apparent to those skilled in the art, by referring to the accompanying drawings:
Fig. 1 illustrates the fertile window based on changes in skin temperature during the menstrual cycle;

Fig. 2 illustrates the fertile window based on change in resting heart rate during the menstrual cycle; and

Fig. 3 illustrates the fertile window based on skin temperature as well as change in resting heart rate during the menstrual cycle.

DETAILED DESCRIPTION OF THE INVENTION

[0016] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. The detailed description of the appended drawings is construed as a description of the currently preferred embodiment of the present invention and does not represent the only form in which the present invention may be practiced. This is to be understood that the same or equivalent functions may be accomplished, in any order unless expressly and necessarily limited to a particular order, by different embodiments that are intended to be encompassed within the scope of the present invention.

[0017] Furthermore there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. It is further understood that like reference numerals refer to identical or functionally similar elements which work together and the use of relational terms such as upper and lower, top and bottom, if any, are used solely to distinguish one from another entity, item or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions.

[0018] Tracking the fertile and infertile days of women during their menstrual cycles helps them to avoid or encourage pregnancy. Traditionally, the Fertility Awareness-based Methods (FAMs), also called the natural family methods, are considered the best approach to track fertility and ovulation, including: temperature method, cervical mucus method and calendar method. One of the best ways is monitoring the basal body temperature early morning, i.e., before getting up in the morning. The manual recording and monitoring of such temperature or other physiological changes is very difficult to perform on a daily basis.

[0019] The present invention discloses a method and a wearable device based on the method, that measures and records physiological parameters of a human female specifically heart rate and temperature. On the basis of the aforesaid parameters, the fertile and non-fertile phase of a female during their menstrual cycle is determined.

[0020] The main aspect of the present invention is a device preferably wearable device for determining female fertile window by measuring physiological parameters particularly the skin temperature and heart rate. The device comprises a temperature sensor, an optical sensor, controller, a battery, a wireless transmitter and a memory cell. The temperature sensor is configured to be in contact with the skin to measure the skin temperature of user. The optical sensor measures the resting heart rate of user. The data obtained from temperature sensor and optical sensor is then processed by controller to determine the fertility window of a woman and the result obtained is transmitted through wireless module of the controller to external cloud-based memory.

[0021] Another aspect of the present invention is a method to determine female fertile window by measuring physiological parameters particularly the skin temperature and resting heart rate. The method comprises obtaining the skin temperature of user from the temperature sensor configured to be in contact with the skin preferably through a wearable device, obtaining the data pertaining to the resting heart rate of user from the optical sensor on said device. Processing the data obtained from temperature sensor and optical sensor by controller to determine the fertility window of a woman and transmitting the obtained result to the external cloud-based memory through wireless module of the controller.

[0022] The present invention provides a process to calculate the shift in resting heart rate, heart rate variability and skin temperature data in order to obtain fertility window, eliminating faulty or irrelevant temperature readings obtained from skin temperature recording.

[0023] The working of the present invention can be best explained by the description in the following phases of menstrual cycle in a female occurring at an average 28 days:
• Menstrual phase (From day 1 to 5)
• Follicular phase (From day 1 to 13)
• Ovulation phase (Day 14)
• Luteal phase (From Day 15 to 28)

Menstrual phase (day 1-5)
[0024] This phase begins on the first day of menstruation and lasts till the 5th day of the menstrual cycle. During this phase the uterus sheds its inner lining of soft tissue and blood vessels which exits the body from the vagina in the form of menstrual fluid.

Follicular phase (day 1-13)
[0025] Follicular phase also begins on the first day of menstruation, but lasts till the 13th day of the menstrual cycle. During this phase the pituitary gland secretes a hormone that stimulates the egg cells in the ovaries to grow. One of these egg cells begins to mature and it takes 13 days for the egg cell to reach maturity.

Ovulation phase (day 14)
[0026] On day 14th of the cycle, the pituitary gland secretes a hormone that causes the ovary to release the matured egg cell which is swept into the fallopian tube.

Luteal phase (day 15-28)
[0027] This phase begins on the 15th day and lasts till the end of the cycle. During this phase the egg cell released during the ovulation phase stays in the fallopian tube for 24 hours and if a sperm cell does not impregnate the egg cell within that time, the egg cell disintegrates.
The hormone that causes the uterus to retain its endometrium gets used up by the end of the menstrual cycle causing the menstrual phase of the next cycle to begin.
[0028] The present invention measures the skin temperature and resting heart rate of a human female over two-three menstruation cycle. The data obtained during these cycles are used to predict the fertility window of a female human over the next menstruation cycles.

Step I: Obtaining the skin temperature of user from temperature sensor
[0029] Fig. 1 presents an embodiment of the present invention wherein the temperature method is applied that involves calculation of lowest body temperature in a day continuously by recording the temperature at regular time intervals for predicting the fertility window.

A. The said method of calculating lowest body temperature requires the female to wear the disclosed wearable device during an extended overnight period of 300 minutes i.e. for example, 2:30 AM till 7:30 AM. However, this duration of recording the temperature may vary from individual to individual. The temperature sensor in the wearable device records the skin temperature obtained continuously every 10 seconds. A total of 1800 readings of temperature are recorded.

B. The dataset of temperatures obtained by the temperature sensor in the wearable device is split into slices of 3 minutes with a total of 100 slices, wherein each slice comprises 18 temperature readings. There may be some faulty or irrelevant data existing in the dataset thus obtained. Hence, the same is identified and eliminated to obtain a set of non-eliminated relevant data. Thereafter, a set of 100 mean values of temperature are obtained by calculating mean value of non-eliminated temperature data in each slice.

C. The final data set obtained from the non-eliminated temperature data after calculating the mean values, is then split into 10 sub-slices, where each sub-slice comprises 10 mean values. For each sub-slice, the deviation check is performed to get the valid data by comparing the maximum and the minimum mean values in the dataset. If the difference between the maximum and the minimum mean values in the dataset is greater than 0.5, then those value are considered as invalid. The lowest mean value in the dataset, thus obtained, is considered to be the indicative temperature data during the period of measurement.

D. The steps disclosed in from A to C in the method are repeated over multiple overnight
periods, and a dataset of indicative temperatures is accumulated. For example, for a user the temperature shift occurred is recorded over time interval D1 to D3 during which the indicative temperature value rises, as shown in Figure 1.The rise detected is indicative or predictive of user fertile window, wherein the indicative temperature data is not the maximum or minimum temperature obtained during the extended period. This shift, occurred in indicative temperature data obtained over the extended period, is interpreted in accordance with a cumulative sum (CUSUM) statistical test.

Obtaining the Threshold values to evaluate the transition periods
[0030] As shown in Fig 1, the indicative temperature values in follicular phase are lower than in luteal phase. The change in temperature during follicular phase from higher value to lower value is indicated by D1 during which the temperature value is below a lower threshold value TTlow. D2 can be determined based on detecting the end point when values of indicative temperature starts rising above defined lower threshold value TTlow. The change in temperature from low to high in luteal phase indicated by D3 where indicative temperature value exceeds an upper threshold TThigh.

[0031] The threshold values TThigh and TTlow are calculated for individual users as:
TThigh = p*Tmax where Tmax is maximum indicative temperature obtained in a menstrual cycle and value of p lies between 0.9 – 1.
TTlow = q*Tmin where Tmin is minimum indicative temperature obtained in a menstrual cycle and value of q lies between 1 – 1.1

Step II: Methods of Eliminating Faulty Temperature Data
[0032] The temperature readings obtained from the temperature sensor on the wearable device may be faulty or irrelevant. The present invention discloses several methods of identifying and eliminating said faulty or irrelevant temperature data comprising –

- The temperature reading between 34 – 41oC is considered to be the normal body temperature for female and is considered valid. Whereas the temperature reading outside the range of 34 – 41oC is disregarded;
- In a case where the difference between two consecutive temperature readings is found to be greater than 0.2 oC, the temperature data which is deviating more from the median of slice’s dataset is considered as faulty and is eliminated;
- In another case, if the difference between the maximum and the minimum temperature readings within a slice is less than 0.3 oC, the temperature data is retained within the slice; whereas, if the difference between the maximum and the minimum temperature readings is between 0.3 oC to 0.5 oC, the deviation correction is performed to retain the temperature within the slice. However, if the difference is greater than 0.5 oC, there is a greater deviation in the temperature data which is considered as invalid within the slice and hence disregarded.

Step III: Obtaining the fertility data pertaining to heart rate of user from optical sensor
[0033] The present invention also discloses the second step i.e. the resting heart rate method to predict the female fertility window. This step uses the optical sensor in the wearable device to measure the resting heart rate of a human female during the menstruation cycle. In this method, a controller is configured to determine the change in resting heart rate preferably in night during sleep when the user is in calm, relaxed state and there is no physical or mental stress on body due to which resting heart rate values might not fluctuate heavily. This method is used to obtain the female fertility window for a user based on the change in resting heart rate during time interval (D4 and D6) as illustrated in Fig. 2. For the purpose, the heart rate is calculated periodically for specific interval of time and the typical heart rate value lies in between 60 – 100 beats per minute. The range of change in resting heart rate values during change of phase from follicular to luteal in menstruation cycle is 10 - 15 heartbeat per minute.
[0034] Fig. 2 illustrates D4indicatinga change in resting heart rate from relatively higher to relatively lower value for a user. For example- for a user the starting point of the fertility window is predicted by the time D5.D5is indicative of end point of a period with relatively lower value of resting heart rate. D6 indicates end point of fertility window where there is change in resting heart rate from relatively lower value to relatively higher value.

Obtaining the Threshold values to evaluate the transition periods
[0035] As shown in Fig 2, the resting heart rate in follicular phase is lower than that in luteal phase. The change in resting heart rate during follicular phase from higher value to lower value is indicated by time D4 during which resting heart rate value is below a lower threshold value RTlow. The change in resting heart rate value from low to high in luteal phase is indicated by time D6 when resting heart rate value exceeds an upper threshold RThigh.

[0036] The threshold values RThigh and RTlow are calculated for individual users as:
RThigh = r*Rmax where Rmax is maximum resting heart rate value obtained in a menstrual cycle and value of r lies between 0.8 – 1
RTlow = s*Rmin where Rmin is minimum resting heart rate value obtained in a menstrual cycle and value of s lies between 1 – 1.2

Step IV: User-specific Fertile Window Calculation based on Resting Heart Rate and Temperature data obtained in Step III and Step I
[0037] The user-specific fertility window (F1, F2)is obtained based on weighted average of temperature and resting heart rate values of fertility window. The fertility start and end time values of temperature obtained in Step I and resting heart rate based window calculation obtained in Step III are then processed to obtain the accurate fertility window. The respective start and end time values obtained in Step I and Step III are assigned weighting coefficients and thus obtaining the user specific fertile window (F1, F2).

[0038] This fertile window is calculated as

[aD5 + (1 – a) D2, bD6 + (1 – b) D3]

where a, b lies between 0.25 – 0.3

[0039] D2 and D5 indicates the start of fertility window based on the data obtained in Step I and Step III respectively, which is processed as per the aforesaid formula to obtain the start of fertility window F1.

[0040] D3 and D6 indicates the end of fertility window based on the data obtained in Step I and Step III respectively, which is processed as per the aforesaid formula to obtain the end of fertility window F2.

[0041] Therefore, the fertility window obtained based on weighted average of temperature and resting heart rate value predict the most accurate fertile and infertile days of female human during her menstrual cycles thereby helping in avoiding or encouraging pregnancy.

[0042] The invention is defined by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued. Moreover, all the details can be replaced by other technically equivalent elements and numerous modifications, such as in shapes and dimensions, can be made according to requirements by a technical expert in the sector to the invention as described in the foregoing, without forsaking the scope of the invention as claimed in the following.

Claims:WE CLAIM:
1)A device configured to be worn in contact with the skin of user preferably female human for determining fertility window (F1, F2) , comprising:
a temperature sensor to obtain skin temperature;
an optical sensor to obtain heart rate;and
a controller to determine the fertility window (F1, F2) using data obtained from the temperature sensor and optical sensor;
wherein
said temperature sensor is configured to obtain skin temperature data overnight at regular intervals and send it to controller for processing the data to determine the indicative temperature for a day and obtain the fertility window (D2, D3) using the temperature method;

said optical sensor is configured to obtain the heart rate data overnight or at relaxed state at regular intervals and send it to controller for processing the data to determine the change in resting heart rate and obtain the fertility window (D5, D6) using the resting heart rate method; and

said controller then determines the weighted average of start point values (D2 and D5) and end point values (D3 and D6) of fertility window(s) obtained from temperature method and resting heart rate method to predict the user specific fertility window (F1, F2).

2) A method (temperature method) for predicting fertility window (D2, D3) in a female human during menstrual cycle using skin temperature, wherein the method comprises:

taking measurements of skin temperature using temperature sensor during an overnight period preferably in every 10 seconds for 300 minutes during menstruation cycle to obtain dataset 1 and sending it to controller for further processing;

splitting of dataset 1 into slices of 3 minutes with a total of 100 slices, where each slice comprises 18 temperature readings;
eliminating faulty temperature readings to from each slice;

said faulty temperature readings include readings outside 34 °C - 41°C , difference between two consecutive readings greater than 0.2 °C and the difference between the maximum and the minimum temperature readings in a slice greater than 0.5 oC;

calculating mean value of each 100 slice and splitting the slices into 10 sub-slices, where each sub-slice comprises 10 mean values;

performing deviation check for all the mean values in each sub-slice to get the valid data
by eliminating the maximum and minimum mean values if their difference is greater than 0.5;

considering the lowest mean value of temperature in the dataset to be the indicative temperature data;

performing the aforesaid steps over multiple overnight periods, to collect a dataset of indicative temperatures; and

determining starting point (D2) of the fertility window wherein indicative temperature value starts rising above lower threshold value (TTlow) and end point (D3) of fertility window wherein indicative temperature value exceeds an upper threshold value(TThigh).

3)The method as claimed in claim 2, wherein said temperature method involves taking multiple measurements of body temperature preferably between 2:30 AM to 7:30 AM.

4)A method (resting heart rate method) for predicting fertility window (D5, D6) in a female human during menstrual cycle using resting heart rate data, wherein the method comprises:
recording the heart rate per minute periodically in a specific time interval using optical sensor over the menstrual cycle and sending it to controller for further processing; and
determining starting point (D5) of the fertility window which is end point of a period with relatively lower threshold value (RTlow) of resting heart rate and end point (D6) of fertility window where there is change in resting heart rate from relatively lower value to relatively higher value, exceeding upper threshold value (RThigh).
5)The method as claimed in claim 4, wherein the heart rate is recorded periodically for specific interval of time, preferably in the night or resting time when the typical heart rate value lies in between 60 – 100 beats per minute.
6)A method for predicting fertility window (F1, F2) in a female human during menstrual cycle using data obtained from skin temperature method (D2, D3) and resting heart rate method (D5, D6), wherein the method comprises:
obtaining the weighted average of start point values (D2, D5) and end point values (D3, D6) of fertility window(s) obtained from temperature method (D2, D3) and resting heart rate method (D5, D6) to predict the user specific fertility window (F1, F2); and
using weighting coefficients (a, b) depending upon the user while determining the average.