How does it work?

OvuSense is different from anything else you may have heard of, or used previously to monitor your fertility. That's because it is a family of products designed to meet your needs at every step of your fertility journey.

What are the benefits?

The patent protected OvuCore Sensor technology solves the issues caused by other methods by taking multiple overnight Core Body Temperature (CBT) measurements in the vagina using a thermistor with a resolution of 0.003 degrees Celsius [a], the OvuSense algorithm intelligently filters the data, and then applies smoothing techniques to provide a clear curve and the truest representation of the action of progesterone on the ovaries. Using the OvuCore Sensor, your OvuSense App confirms the date of ovulation with 99% accuracy [b][d]. Unlike the other methods it is also able to predict ovulation in real time - the published literature shows it does this with an accuracy of 89% and a positive predictive value of 96% [c][d].

The OvuFirst Sensor also solves some of these issues caused by other methods by taking multiple overnight skin temperature measurements using an identical set of components to our revolutionary patent protected OvuCore Sensor technology: it has a thermistor with a resolution of 0.003 degrees Celsius [a], the OvuSense algorithm intelligently filters the data avoiding the problems caused by 'dropouts' experienced by other skin based monitors, and then applies smoothing techniques to provide the clearest possible curve provided by a skin measuring method. Using the OvuFirst Sensor, your OvuSense App confirms the ovulation window with suggested date of ovulation with over 90% accuracy [e].

[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 100 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] Internal Fertility Focus side by side study of OvuFirst and OvuCore Sensors (2021), documented as a class II medical device in the notified body reviewed CE Certificate Technical File.

How do they work?

Fertility Tracker Apps (FTAs) use the calendar based method of tracking. You input the dates of your period and the app will calculate your ovulation based on the assumption that you have 'middle of the month' ovulation. Some have more sophisticated algorithms which accept manually entered oral temperatures, or Ovulation Predictor Kit (Luteinizing Hormone) test results.

How close will the results be compared to OvuSense?

Even though Fertility Tracker Apps (FTAs) sometimes allow you to enter information other than just your period dates, they are not able to pinpoint the date of ovulation with useful accuracy because they are based on the assumption that all women have very regular cycles with ovulation that occurs in the 'middle of the month' Of all the methods for looking at your ovulation you need to know that FTAs are the least reliable, and you should really ignore the results they produce if you're struggling to conceive.

What are the benefits?

Fertility apps are convenient and a handy way of tracking the basic information in your cycle. They help you stay organised and often feature useful extra information to help with conception and pregnancy.

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 [1]. A recent study into several fertility apps concluded 'as a result of the physiological variations of the menstrual cycle length and ovulation day, the fertile window cannot be predicted easily, and it has to be determined during the ongoing cycle. Therefore, to help couples wishing to conceive, apps based on data from previous cycles alone are not suitable to indicate the most fertile days' [2]. Another recent study concluded 'accuracy of ovulation prediction [using previous cycle data] was no better than 21%' [3]. Other studies have drawn similar conclusions [4].

[1] Baird D, McConnaughey D (1995); Lenton EA, Landgren BM (1984a); Lenton EA, Landgren BM (1984b)
[2] Freis A, Freundl-Schütt T (2018)
[3] Johnson S, Marriott L (2018)
[4] Freundl G, Godehardt E (2003); Moglia ML, Nguyen HV (2016); Wise LA, Hatch EE (2015)

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%-83%[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)

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)

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);

How does it work?

A serum blood progesterone measurement generally should be obtained approximately one week before the expected onset of the next menses [1] and in a 28 day cycle that's day 21 which is why the test is often called a '21-day progesterone'.

How close will the results be compared to OvuSense?

Serum progesterone is a standard method for confirming ovulation took place that is used by medical professionals throughout the world. It's reliable if your blood is drawn on the right day in your cycle, but it doesn't really provide an accurate day on which ovulation occurred, just a good assessment that it has occurred within a recent window of 5-10 days. If you OvuSense App confirmation fits within that window then it's a good sign but you shouldn't necessarily expect agreement between the results, and very importantly a negative serum progesterone result doesn't necessarily mean you haven't ovulated, particularly if OvuSense shows you have.

What are the benefits?

If timed correctly, a serum blood progestrone is an excellent way of confirming that you have definitely ovulatied in the current cycle. If it is used regularly in successive cycles it can help build up a picture of your ovulation which confirms home testing.

What are the drawbacks?

There is a real practical problem if you have irregular cycles or are in the 70% of women who ovulate at a different time in your cycle from the expected ‘norm’[2], or if you just don't have time to get in to have your blood drawn. Given that a false negative test can occur if the timing of your blood draw is out by even a day, a serum blood progesterone can also lead to the wrong conclusion – potentially setting you on a course of unnecessary treatment.

[1] ASRM (2012) Diagnostic evaluation of the infertile female.; Fertility Assessment and Treatment of people with fertility problems.
[2] Baird D, McConnaughey D (1995); Lenton EA, Landgren BM (1984a); Lenton EA, Landgren BM (1984b)

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 doctor 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)