Thank you for purchasing OvuSense on Amazon

Please note that your OvuSense starter pack cannot be returned for a refund unless the bag containing the OvuSense Sensor is unopened. If you want to find out more about OvuSense before you open it please click here to visit our FAQ page

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Tracking your cycle in real time

Cycle 1

Start using OvuSense immediately by downloading data from your sensor each morning to the OvuSense App. Your temperature is tracked in real time.

After a few days, if you're using the OvuCore sensor, OvuSense can predict the onset of your ovulation without having to wait until the next cycle or rely on historic data.

Three days after you ovulate, OvuSense confirms the exact ovulation date. You can also continue monitoring your temperature to see what's happening with your progesterone levels during your luteal phase.

Cycle 2

Stop using the OvuCore Sensor during your period, recommencing use immediately after it ends. OvuSense will then predict the 8 days you are most likely to conceive in this cycle. If you're using the OvuFirst Sensor you can keep tracking throughout your period.

OvuSense updates the information it provides in real time during the cycle, replacing the 8 day 'long range' window with a 'short range' 4 day ovulation window.

Scroll on the OvuSense App to compare your ovulation dates and your cycle pattern. Real time data can be shared with your partner and/or doctor through the OvuSense Pro clinician portal.

Read about women already using OvuSense

Which fertility monitor is right for me?

Compare OvuSense with other methods for monitoring your ovulation and reproductive cycle.

As you consider which fertility monitor fits you best some typical things to consider are:

How large a fertile window will it detect so you can maximize the time when you're trying to conceive
How accurate is it at confirming ovulation - the less accurate the less chance of it helping you in your next cycle
Can it predict ovulation using the current cycle data - something we like to call realtime prediction
Does the system work for PCOS and irregular cycles
Can it help your doctor screen for fertility issues
Can it help you and your doctor monitor your medication or treatment

Each of the statistics quoted below are derived from clinical evidence available on fertility monitoring methods and products. Pro refers to the OvuSense Pro clinician portal. Click on the 'i' icon next to each method in the table, or directly on the method in the table on mobile devices to find out more about the clinical evidence.

	Feature/ How many does it get right
	Fertile window prediction days	Confirms ovulation	Live ovulation prediction	PCOS and irregular cycles	Screen for fertility issues	Track medications and treatments
OvuFirst (Skin-Worn Temperature)	OF					Pro	Pro
OvuSense OvuCore (Core Body Temperature)	OS Core					Pro	Pro
Fertility Tracker Apps	FTA
Basal Body Temperature	BBT
Skin Worn/ Fertility Bracelet Devices	SW/ FB
Ovulation Predictor Kits and Monitors	OPK/ OPM
Serum Progesterone	SP
Ultrasound	US

OvuSense (OS)

What makes OvuSense different?

The patent protected OvuCore Sensor technology solves the issues caused by other methods by taking multiple overnight continuous Core Body Temperature (cCBT) measurements in the vagina using a thermistor with a resolution of 0.003 degrees Celsius - that means it's reading the differences to 1/1000th of a degree [a].

What are the benefits?

With 99% accuracy for confirming ovulation [b][d], and 96% positive predictive value for predicting ovulation [c][d], our clinical papers show OvuSense can save you up to 15 months trying to conceive compared with other devices. Take a look at the table at the bottom of this page to compare the accuracy of various other methods.

Up to 15 months quicker?

The 15 months difference is calculated as follows: According to clinical studies, your average chance of getting pregnant in any reproductive cycle is around 15%. [e] As a result 75% of the population will conceive within 5 months from the point at which they start out trying to conceive. A 100% accurate device would provide you with an exact understanding of the 8 day fertile window for each of those cycles and do so consistently.

With 99% accuracy, OvuSense provides 7-8 days of the window if your ovulation is regular, so if you're just starting out with regular ovulation timing it should take 5-6 months to get pregnant (100%/14-15%).

Other devices provide accuracies of up to 80% for the fertile window. In a 28 day cycle that means they can be up to 5 days out telling you on which days in your cycle you should try and conceive. With that wrong information your chances of getting pregnant can reduce to around 5% per cycle, and that means it could take up to 20 months to get pregnant (100%/5% =20) instead of 5-6.

What if I have irregular ovulation?

If you have irregular ovulation timing, then you probably already know it may take you longer to conceive. The really important fact is that urine strips and monitors (OPKs) and other temperature devices are much less likely to work for you. OvuSense is tracking the hormone released during ovulation and because it's able to predict that ovulation in real time during your cycle, it does work.

Urine strips annd monitors use hormones which don't behave as expected if you have an issue like Polycystic Ovarian Syndrome that causes variable ovulation, so you end up with false positive results or no positive results at all. [f] Other temperature devices use your result from a previous cycle to provide your fertile window so they simply don't work if your ovulation occurs on a different day in your next cycle. [g]

Added to the chances of getting pregnant more quickly with OvuSense, there's no messy urine strips, no confusing charts with multiple parameters, and no need to remember to test.

[a] The measuring resolution of a thermometer is the step between each temperature reading - a resolution of a normal 0.1 degree Celsius means a reading may be wrong by as much as 0.099 degrees Celsius, or in other words there are only 3 steps between a wrong and right ovulation result of 0.3 degrees Celsius rise, whereas 0.003 degrees resolution provides 1000 steps.

[b] The accuracy measures how many positive and absent ovulations the device confirms correctly.

[c] The positive predictive value measures how many of the real time predicted ovulations OvuSense gets right.

[d] The accuracy of ovulation confirmation by OvuSense is based on the data set originally published at the 2013 ASRM meeting as a quality index: Papaioannou S, Aslam M (2013), and developed in the key publication outlining the accuracy and positive predictive value of advance prediction of ovulation shown at the 2014 ESHRE meeting: Papaioannou S, Delkos D, Pardey J (2014).

[e] The chances of conceiving in each reproductive cycle are explored in the following clinical paper: Colombo B, Masarotto G (2000) Daily fecundability: first results from a new data base. Demogr Res 3: article 5. .

[f] The following papers together show that urine strips don't work if you have variable ovulation McGovern PG, Myers ER (2004); Irons DW, Singh M (1994); Lloyd R, Coulman CB (1989);

[g] The following papers together show that other temperature monitors and fertility bracelets don't work if you have variable ovulation Freundl G, Godehardt E (2003); Goodale BM, Shilaih M (2019)

Basal Body Temperature (BBT)

How does it work?

Long established in the clinical literature [1], the BBT method aims to help detect the date of ovulation in a cycle by taking the basal (lowest) temperature first thing on waking with an oral thermometer, and then charting the change in this daily temperature throughout the month to determine the date of ovulation. It can also be used if you have regular ovulation for predicting the fertile window in the next cycle. Because a rise in temperature is associated with the release of progesterone which occurs during ovulation, a predictable pattern emerges for most women which can help confirm ovulation took place over a number of cycles.

How close will the results be compared to OvuSense?

Even though the Basal Body Temperature (BBT) method uses temperature as a basis for confirming if ovulation took place, it relies on very different measuring technology from the patented protected system used by OvuSense. Oral thermometers only have an accuracy of around 0.1 degrees Celsius [a] so are not easily able to detect the 0.3 degree rise associated with ovulation with accuracy. Even if you type the values you get with your thermometer into a Fertility Tracker App they are likely to give a different ovulation result from OvuSense. You should also be aware that a vaginal temperature measured using the OvuCore Sensor is generally up to two degrees Celsius higher than temperature readings taken in the mouth, and higher still than external temperature readings such as those taken under the armpit or on the wrist. Lastly, OvuSense uses proprietary algorithms to detect ovulation, so it can produce very different results even with similar looking temperature curves.

What are the benefits?

BBT is a relatively cheap and easy way to track your temperatures and a number of apps are now available which combine the idea of a single oral temperature with automatic charting. It is more effective if combined with cervical mucus tracking.

What are the drawbacks?

Clinical studies show that 70% of women don’t ovulate in the middle of their cycle, and you can ovulate at a different time from cycle to cycle, even if your cycles are always the same length [2]. As a result because BBT relies on predicting the fertile window based on past cycle data, it's of little practical use if you don't ovulate at the same time each month. With or without an app to help, BBT is unable to help predict ovulation using the current cycle data. Again, even with an app, some users find the charting cumbersome and have difficulty taking a valid measurement each day. Studies assess accuracy for confirmation that ovulation took place at around 69%-78%[3].

[1] Barrett JC Marshall J (1969); McCarthy and Rockette (1983) [2] Baird D, McConnaughey D (1995) Lenton EA, Landgren BM (1984a); Lenton EA, Landgren BM (1984b) [3] Freundl G, Godehardt E (2003); Barron M L Fehring R (2005); Bauman JE (1981)

Skin Worn/ Fertility Bracelet Devices (SW/ FB)

How do they work?

A more modern application of the BBT method is to take several consecutive temperature measurements from the skin - either under the armpit, under the bra strap or on your wrist - at various intervals overnight, and then download and interpret these measurements on an app. Some of these devices record additional secondary parameters.

How close will the results be compared to OvuSense?

Even though Skin Worn/ Fertility Bracelet Devices (SW/ FB) use skin temperature as a basis for confirming if ovulation took place, they rely on very different measuring technology from the patented protected system used by OvuSense. They also use different algorithm methods, and you therefore shouldn't expect them to give you the same temperature or ovulation results. You should also be aware that a vaginal temperature measured using the OvuCore Sensor is generally up to two degrees Celsius higher than temperature readings taken in the mouth, and higher still than external temperature readings such as those taken under the armpit or on the wrist.

What are the benefits?

As with the BBT method, a skin worn device is a relatively easy way to track your temperatures and it's often more convenient. The devices help establish the pattern of temperature over time, and because of the volume of measurements, they are possibly a little more consistent in detecting ovulation than BBT with an oral thermometer.

What are the drawbacks?

Measuring temperature at the skin also has some negative aspects for devices that have not been optimised through side by side clinical testing with 'gold standard' methods. Firstly, the skin temperature tends to vary in opposition to core temperature changes associated with the release of progesterone, and secondly there is a high chance of 'dropouts' in the temperature signal because it's difficult to maintain contact between the skin and sensor consistently. Just as with BBT, these devices rely on predicting the fertile window based on past cycle data, so they are more suited to women with regular cycles.[2] They are unable to predict ovulation using current cycle data. There are no current papers assessing accuracy of the ability to confirm the date of ovulation, but published data for a wrist worn device shows a sensitivity of 81% (missing around 19% of ovulations) and an ability to confirm that ovulation took place within a fertile window (though not on which day) with a 'F score' of 0.78 which indicates 78% accuracy [3].

[1] Barrett JC Marshall J (1969); McCarthey and Rockette (1983)
[2] Baird D, McConnaughey D (1995); Lenton EA, Landgren BM (1984a); Lenton EA, Landgren BM (1984b)
[3] Goodale BM, Shilaih M (2019)

Ovulation Predictor Kits and Monitors (OPK/ OPM)

How do they work?

Ovulation Predictor Kits (OPKs) provide a positive test for Luteinizing Hormone (LH) using a urine test strip. Ovulation Prediction Monitors (OPMs) usually allow multiple ovulation predictor urine strip results to be combined to provide a monitoring picture of Luteinizing Hormone (LH) over a cycle. Some monitors use a urine strip that combines LH with E3G - a metabolite that allows assessment of the estradiol level.

How close will the results be compared to OvuSense?

Firstly, OPKs and OPMs are only able to provide a prediction of when ovulation may occur during the current cycle. They are not able to confirm you have ovulated, and because of the lack of confirmation they cannot be used to reliably predict your fertile window for the next cycle. When you're using the OvuCore Sensor your OvuSense App will also provide you with a prediction of when you are about to ovulate using the current cycle data. As this is based on the temperature pattern caused by the release of progesterone associated with ovulation, rather than luteizing hormone, it may well provide you with a different prediction. This is particularly true if you have an ovulatory issue such as PCOS which is known to interfere with OPK and OPM results. However, if your OvuSense App and an OPK or OPM predict the same day for ovulation then this can be very useful in confirming your hormone behaviour throughout the cycle.

What are the benefits?

LH peaks up to a day in advance of ovulation so OPKs and OPMs are helpful in providing a short term indication of when you should try and conceive based on your current cycle data. They work well at predicting ovulation for most women that have regular 'middle of the month' ovulation. The addition of E3G with OPMs helps provide a fertile window prediction and storing multiple results in the monitor helps with the convenience and monitoring over time compared with OPKs.

What are the drawbacks?

OPKs are known to give false positive results for women with PCOS and other ovulatory issues [1]. They sometimes also give false negative results, which can be based on the cutoff point of the test, or simply that the test is not optimised for the natural level of LH for the particular user. OPKs can only provide a snapshot at one point in time in your cycle, meaning you have to use a minimum of two tests a day over a 10-20 range in each cycle to monitor where you are in your cycle. The manufacturers make valid claims for 99% accuracy in detecting LH, but the accuracy estimates for correct advance prediction of ovulation are 70%-84% depending on the publication [2]. OPKs and OPMs are unable to confirm the date of ovulation or if you haven't ovulated. They are sometimes thought to be messy, impractical and the cost quickly adds up. Lastly, they cannot be used for clinical monitoring as they only provide a picture up to the point of ovulation and no understanding of what happens during ovulation itself, and the luteal phase.

[1] McGovern PG, Myers ER (2004)
[2] Irons DW, Singh M (1994); Lloyd R, Coulman CB (1989);

Ultrasound (US)

How does it work?

3-4 ultrasound 'folliculometry' scans per cycle is the suggested requirement of good cycle monitoring. Your clinician will usually be looking for a dominant follicle (the next one that is most likely to rupture resulting in ovulation) of 20mm or more in size in one of your ovaries. This measurement means that you are likely to ovulate in the next 24-48 hours.

How close will the results be compared to OvuSense?

Ultrasound 'folliculometry' is the accepted 'gold standard' assessment of ovulation as it's the only method which actually 'shows' ovulation about to take place or that it has taken place. It is really important to understand the prediction your OB/GYN or specialist gives you when saying you are going to ovulate having completed an ultrasound is based on an assessment of the size of your 'dominant follicle' which is assumed to be the same for all women. This means ovulation can occur in a window of 12-72 hours after your scan, or in fact may not occur at all, and the only way to confirm this is to go back for more scans in the same cycle. Ideally if you have a scan on one day and the follicle hasn't 'ruptured', and you have another scan on the next day and it has, then you know you ovulated in between - otherwise it can only be used as a guideline for the ovulation window.

What are the benefits?

If timed correctly, ultrasound 'folliculmetry' is the accepted gold standard for confirming the likelihood of ovulation in a cycle [1]. It is also essential in assessing the growth and number of follicles, particularly during stimulation of the ovaries, and vital in diagnosis of ovarian issues such as PCOS.

What are the drawbacks?

Ultrasound ‘folliculometry’ is not always a good predictor of ovulation, and this isn’t surprising given that it assumes that all women of whatever size and shape, or hormonal make-up will have identically sized follicles just before ovulation occurs. Dominant follicle size can vary greatly [2]. Katiyar et al. (2018) reported on the ability of ultrasound folliculometry to predict ovulation in 100 infertile women, concluding folliculometry predicted ovulation with an accuracy of 86% with a specificity of 58.6% and a sensitivity of 98.6% [3]. Also, because a scan is a snapshot at one point in time in your cycle, timing the scan correctly is essential, and a number are needed in cycles where the timing of ovulation needs to be known. This is often impractical for the patient and the clinic.

[1] ASRM (2012) Diagnostic evaluation of the infertile female.; NICE (2004). Fertility Assessment and Treatment of people with fertility problems.
[2] Vlaisavljević V, Došen M (2007)
[3] Katiyar S, Arya S (2018)

Fertility Testing Methods Key

OF OvuFirst (Skin Temperature)
OS Core OvuSense OvuCore (Core Body Temperature)
BBT Basal Body Temperature
FTA Fertility Tracker Apps
SWD Skin Worn Devices
FBD Fertility Bracelet Devices
OPK Ovulation Predictor Kits (urine strips)
OPM Ovulation Prediction Monitors (urine strips)
SP Serum Progesterone
US Ultrasound

Thank you for purchasing OvuSense on Amazon

Please note that your OvuSense starter pack cannot be returned for a refund unless the bag containing the OvuSense Sensor is unopened. If you want to find out more about OvuSense before you open it please click here to visit our FAQ page

Tracking your cycle in real time

Cycle 1

Cycle 2

Which fertility monitor is right for me?

OvuFirst (OF)

How does it work?

What are the benefits?

Clinical Publications

OvuSense (OS)

What makes OvuSense different?

What are the benefits?

Up to 15 months quicker?

What if I have irregular ovulation?

Fertility Tracker Apps (FTA)

How do they work?

How close will the results be compared to OvuSense?

What are the benefits?

What are the drawbacks?

Basal Body Temperature (BBT)

How does it work?

How close will the results be compared to OvuSense?

What are the benefits?

What are the drawbacks?

Skin Worn/ Fertility Bracelet Devices (SW/ FB)

How do they work?

How close will the results be compared to OvuSense?

What are the benefits?

What are the drawbacks?

Ovulation Predictor Kits and Monitors (OPK/ OPM)

How do they work?

How close will the results be compared to OvuSense?

What are the benefits?

What are the drawbacks?

Serum Progesterone (SP)

How does it work?

How close will the results be compared to OvuSense?

What are the benefits?

What are the drawbacks?

Ultrasound (US)

How does it work?

How close will the results be compared to OvuSense?

What are the benefits?

What are the drawbacks?

Fertility Testing Methods Key