How to Choose the Right Fertility App and Monitor
Guest post by Kate Davies
Have you considered using a fertility app or monitor to help you conceive? With so many available, you may feel confused about which one to try and you are not alone; my patients tell me that they feel really bewildered as to which is the best fertility App or Monitor to use. Recent media attention based on research studies highlighted that fertility apps used alone are generally ineffective and do not accurately show a woman when she should try and conceive (Setton et al. 2016; Duane et al. 2016), resulting in even greater confusion.
In this article, I review the most commonly used fertility Apps and Monitors, explain what they are, how they work and who they are useful for.
Most importantly, I review their accuracy, including their ability to identify fertile days and ovulation, as well as considering the customer support they offer and the all-important cost. However, before I start it’s really important to explain one crucial difference between fertility apps and monitors.
The difference between Fertility Apps and Fertility Monitors
There are many fertility apps that you can download to use on your smartphone, and many are free. Used alone, these apps calculate your fertile time using a calendar method. These apps rely on traditional thinking about predicting the ovulation, which is based on the assumption that ovulation consistently occurs 14 days before the onset of your next period – so in the ‘middle of your cycle’ if you have a 28-day cycle. In fact, we now know that only a small percentage of women ovulate exactly 14 days before the onset of their period (Baird et al. 1995; Lenton et al. 1984 a & b). So the calendar method is often really ineffective, and all these apps are doing is keeping an electronic diary – more detailed and convenient than writing your cycle down on paper, but not much more than that.
Some fertility apps go a step further by taking into consideration how long your previous cycle lasted. The problem here is that ovulation timing can vary even when you have consistent cycles, data from previous cycles don’t provide enough information to reliably predict individual fertility. Even though there is no doubt that tracking your fertility enables you to take some control and leads to a greater awareness of your cycle, to increase reliability and to be beneficial for conceiving, you need to observe the physiological signs of fertility as well. This is where a fertility monitor comes in.
Fertility monitors used in conjunction with apps offer greater reliability. As well as tracking your cycle, a monitor gives you the ability to track your progesterone level by measuring temperature. There are two types of temperature which can be monitored: basal body temperature or core body temperature.
The most accurate method of tracking basal body temperature is by measuring in the mouth. A number of skin based monitors also exist, but recent studies have shown this is not a particularly accurate method (Rollason et al. 2014; Wark et al. 2015) as it is subject to temperature disturbances due to environment and illness.
Studies have shown that the most accurate method of tracking temperature is to measure core body temperature in the rectum or vagina. The ability of core temperature, as opposed to oral or skin based temperature, to more accurately track the level of progesterone and to provide real time prediction of ovulation is confirmed by Coyne et al. (2000).
Here’s why measuring temperature is a good idea:
Progesterone is released during the process of ovulation in each cycle, and your progesterone level will normally stay high for the rest of your cycle after ovulation.
As progesterone is released, it causes your body temperature to rise, and the rate of rise of temperature is directly linked to the rise in progesterone level. Measuring temperature allows us to see when ovulation occurs. Detecting if and when you ovulate is vital to increase your chances of conception.
The key things to consider in tracking temperature is how often the measurements are taken, when the measurements are taken (overnight or first thing on waking is when the temperature is at its most stable), and most importantly the location of the sensor.
Another recognized fertility indicator is cervical mucus. Observed throughout the cycle, cervical mucus changes in appearance and consistency and stretchy, egg white secretions indicate peak fertility. Some Apps allow you to record these secretions.
The Most Commonly Used Fertility Apps and Monitors (in alphabetical order):
Ava is a wristband worn at night, which is used in conjunction with an app. The makers claim the monitor observes physiological data such as skin temperature on the wrist to monitor progesterone levels, as well as pulse rate, heart rate variability, profusion, bioimpedance, breathing rate, heat loss, movement and sleep and state that “some of these parameters change in correlation with reproductive hormones.” Ava identifies 5.3 fertile days per cycle, with 89% efficacy, but is unable to detect ovulation. We can assume it takes multiple readings of these parameters.
You can use Ava if your cycles range between 24-35 days. However, if you have an ovulatory issue such as Polycystic Ovarian Syndrome (PCOS), then Ava is unlikely to work for you. Ava provides customer support in the form of FAQ’s and email support. The manufactures don’t say whether the email support is clinical or technology based.
Cost – $299/£152 + Shipping.
Delivery time – 6-8 weeks.
My opinion –
Ava is a combination of a lifestyle and fertility monitor. If monitoring your general health is the most important aspect for you then you might like this, but due to its low efficacy and inability to detect ovulation, I wouldn’t recommend it for fertility.
2. Clearblue Fertility Monitor
The Clearblue Fertility Monitor detects changes in two key fertility hormones luteinising hormone and oestrogen present in the urine. It is able to identify 6 fertile days and states it is 99% accurate in detecting the LH surge.
You can contact Clearblue via Live Chat and email or by the telephone careline where women can get both technical support and advice on their journey to parenthood.
Cost – Clearblue Fertility Monitor $104.00 subsequent ovulation tests from $38.98/30 tests
My opinion –
The Clearblue monitor offers women a practical and clear way of identifying the fertile. The monitor, however, is not suitable for women with PCOS due to elevated levels of LH or women who are using fertility treatment medication such as Chorionic Gonadotrophin (HCG) or Clomid as this can cause elevated oestrogen levels. For those reasons, this monitor would not be accurate for a large percentage of women who are trying to conceive.
To achieve accurate results, you need to test on multiple days leading up to ovulation. This can be inconvenient but also requires purchasing subsequent ovulation tests.
Clue is a cycle tracking app that uses the calendar method to predict your cycle. You are also able to input any symptoms you experience such as bleeding, pain, emotions and energy.
Clue offer App technical support only via their website.
Cost – Free App
My opinion –
If you want to get more knowledgeable on your cycle and understand more about your body then you may like using this app. It is user friendly and nice to look at, but it is it unlikely to help you conceive any more than using a paper diary or wall calendar.
Daysy is a fertility monitor and app that monitors basal body temperature with one quick reading on waking, using an oral thermometer. The makers claim the monitor identifies fertile days with 99.3% accuracy and learns your individual cycle pattern, which it then uses to forecast your next cycle. Daysy does not appear to confirm ovulation. The product comes from the makers of BabyComp/ LadyComp which was included in an original paper on cycle monitors by Freundl et al. (2003), showing similar accuracy figures.
The Daysy app offers you some fun features such as a gender prediction tool, however research does not support gender prediction based on the timing of sexual intercourse in a given cycle (Wilcox et al. 1995). The app also allows you to share information with your partner to let him know when it is ‘time to get down to business’! Unfortunately, you can’t use Daysy if you have irregular cycles, and therefore it is unlikely to work for women with ovulatory problems too.
Daysy offers various customer support such as FAQ’s, video tutorials and downloads and the makers claim the product can be used to avoid pregnancy as well as to achieve pregnancy.
Cost – $330/£256 for thermometer, Free app + Shipping
Delivery time – not stated
My opinion –
Daysy offers an 21st century alternative to manual temperature charting but it is debatable whether it does anything more than your average ‘under the tongue thermometer’. Oral temperature recording is subject to environmental disturbances and illness, and it is therefore not the most accurate method. This, combined with the price, would be a non-starter for many women.
5. Fertility Friend
Fertility Friend is a widely-used cycle tracking app that incorporates manually entered oral temperature readings and other physiological data in to its system. Temperature readings are taken using a basic oral thermometer and users are encouraged to input cervical secretions, sexual intercourse and other physiological data.
The app is able to confirm ovulation based on the manually entered temperature readings and offers an indication of fertile days but is unable to predict ovulation.
Wise et al. (2015) concluded in their recent randomized trial that in a population of women who had been trying to conceive for ≤6 cycles at study entry there is “little evidence that randomization to the Fertility Friend menstrual cycle charting software program influenced fecundability among pregnancy planners participating in an incentive-based internet study.” It does go on to say that “among those who had already been trying to conceive for 5-6 cycles at enrollment, assignment to Fertility Friend was associated with faster conception.” The study showed a ~15% improvement in that group, which is almost certainly down to the charting creating a better overall understanding of their cycles. However, it is difficult to translate this result into a greater likelihood of conception in women who have any kind of irregular cycles and/ or ovulation. As with any basal body temperature monitoring, the temperature is just as prone to variations for women with irregularity, and are not able to predict ovulation in real time.
Fertility Friend offers support via access to a community and helpful videos.
Cost – Free. There is a cost to upgrade to access other features.
My opinion –
Fertility Friend offers a woman an easy and convenient way of charting her cycle and fertility indicators. However, having looked at many Fertility Friend charts, it is common for me to see inaccuracies with the confirmed date of ovulation and fertile days. This is most often with an earlier ovulation date than would be expected by observing the temperature data by eye. This may be down to the detection algorithm Fertility Friend employs, but either way the literature would indicate as with other apps that there is little benefit in efficacy compared with manual charting.
Flo is another period tracking app and an ovulation calendar. It uses AI to increase its prediction accuracy to help women understand their cycle.
The app offers daily health insights and analytical reports on your period and lifestyle. The app provides support via email and community groups to engage with on topics from healthy eating to anxiety and depression. However, at the time of writing these groups do not seem active.
Cost – Free App but £7.49 / $10.00 per month to unlock unlimited access for further support.
My Opinion –
The Flo app offers you a great deal of advice at your finger tips via their many informative articles. It is disappointing to see that the Flo community is not active; this could be because it’s a recent initiative, as it is a great idea. However, there is no getting away from the fact that, like Clue, this is yet another calendar tracking device and as such is not reliable at identifying ovulation.
With the FitBit Versa watch, Charge 3, or Ionic devices, you are able to track your female health via the in-app experience. It is designed to help you learn more about your menstrual cycle and your body.
The app allows you to log your period, record symptoms, and receive notifications of when your period is due. The app is also able to give you an average estimated ovulation day.
Fitbit has a Female Health Forum Community, but it appears that this is for technical help rather than female health support and advice.
Cost – Prices vary depending on device from $170.75- 328.00/£129.99-249.99
My Opinion –
FitBit offers you the ability to get to know your menstrual cycle and symptoms so you can better understand how your menstrual cycle effects your energy levels, mood and general well-being. It also helps you to plan around your cycle, such when you’ll have better energy and when a rest day is best! However, FitBit does not use any physiological data such as temperature, and is therefore a calendar tracking advice, and as such is not able to reliably predict ovulation or when your next period will occur.
Glow is a cycle tracking and lifestyle app that allows the user to input physiological data. However, the website tells you very little about what you are actually monitoring in terms of fertility.
Glow has a thriving online community and offers support through FAQ’S. The app claims to also monitor male fertility; I wonder how it does that!
Cost – Free app
My opinion –
Glow has been heavily criticized in the recent Fertility app study. It appears to provide more lifestyle data benefits than others, and if a lifestyle App is your thing then this might be for you.
9. Natural Cycles
Natural Cycles is an app that is used with a basal body temperature thermometer. A single temperature reading is taken first thing in the morning, and this information is then downloaded to a smartphone.
Natural Cycles uses an algorithm that quickly learns your cycle and the company state is able to detect and predict ovulation and when you are fertile. Two clinical studies in to the use of Natural Cycles conclude that this method is accurate in identifying a users ovulation day and fertile window.
Natural Cycles offers FAQ and email support for an additional cost.
Cost – $79.99/year or $10/month
Delivery Time – 3-5 days in Europe and 6-7 in the rest of the world.
My opinion –
If you are looking to monitor basal body temperature and would like an easy to use technology-based option, then this might be right for you. Its inexpensive thermometer makes it more affordable than Wink or Daysy, however this thermometer is measuring basal body temperature only and not the more effective core body temperature.
10. Kindara and Wink
Kindara is a cycle tracking app that is used with Wink – an oral thermometer. Wink monitors basal body temperature using a single measurement each day, and then syncs this information with the Kindara app on your smartphone.
Kindara is able to identify your fertile time and confirm ovulation but offers no ovulation prediction in real time. Kindara states that Wink is the most accurate body temperature thermometer on the market but offers no efficacy rating for its ability to accurately identify the fertile time or confirm ovulation. It unclear whether Kindara works for women with irregular cycles.
Kindara offers support via email only. Charts can be shared with your clinician via the Practitioner Portal.
Cost – $129
Delivery time – Not stated
My opinion –
The Kindara app and Wink thermometer are certainly appealing to the eye. The thermometer is easy to use and read. However, like Daysy and Natural Cycles, you are essentially paying for an oral thermometer.
11. Leaf (Bellabeat)
Leaf, made by Bellabeat is a reproductive health tracker in the form of wearable jewelry. Leaf syncs with your smartphone and tracks your activity, apparent stress levels and sleep to give you information about your cycle.
Leaf uses the calendar method to predict ovulation, based on your previous cycle and the date of your last period, rather than any of the measurement parameters.
Leaf offers support via FAQ’s, a telephone call back service and pictorial tutorial to help with the technical side.
Cost – Prices vary by style. Check their website.
Delivery time – Not stated
My opinion –
If you are looking for a nice piece of jewelry and a lifestyle tracker, then Leaf might be just what you need. However, it is not a true fertility monitor, and if you really want to get knowledgeable about your cycles and accurately predict ovulation then I strongly recommend looking elsewhere.
12. Mira –
Miracare.com is similar to MyLotus in that it is a personalized fertility testing device and app that allows you to monitor your luteinising Hormone (LH) levels and how this links to ovulation and the identification of your fertile days. Mira costs: $250.00 / £199
My opinion – Mira is certainly the next generation of ovulation prediction using LH in the urine. Similar to MyLotus, Mira claims that the device is suitable for women with irregular cycles and PCOS however, there is no reference to the device having been tested by women with these cycle characteristics, and therefore it is difficult to substantiate this claim. Mira also has a ranking system on their website and ranks their product against other methods such as BBT (basal body temperature), Ovulation Predictor Kits (OPKS), and Fertility Apps. It does not rank itself against true fertility monitors with clinical trials and evidence behind it, such as OvuSense which is interesting.
My Lotus is a personalized fertility testing device and app that allows you to monitor your luteinising Hormone (LH) levels and how this links to ovulation and the identification of your fertile days.
MyLotus measures how much LH is present in your urine. LH levels increase as you prepare to ovulate. All women have a different baseline LH level and MyLotus is able to provide a measured (quantitative) result that differs from traditional (qualitative) ovulation tests. MyLotus state that therefore the device is suitable for women with irregular cycles and women with PCOS.
MyLotus offers technical support via FAQ’s and the ability to report a technical problem within the app. However, it does not appear that MyLotus offers any clinical support.
Cost – MyLotus Starter pack £349.00 thereafter £54.00 for 20 ovulation tests. MyLotus app is free and can be used as a stand-alone calendar tracker.
My opinion –
MyLotus is certainly the next generation of ovulation prediction using LH in the urine. The ability to identify LH increase from a woman’s normal baseline is likely to improve efficacy of the traditional LH testing. However, it is evident that MyLotus was tested on a very small sample size of 111 women over a 12-week period (Note: there is further reference on the website to a sample size of 64 women and therefore exact sample size is unclear).
MyLotus claim that the device is suitable for women with irregular cycles and PCOS however, there is no reference to the device having been tested by women with these cycle characteristics, and therefore it is difficult to substantiate this claim.
Costs can escalate, as subsequent ovulation tests are needed. Some women may find it inconvenient to test multiple times.
Ovacue is a fertility Monitor that measures chloride changes in saliva and vaginal mucus using 2 different sensors. You take one measurement per day. Ovacue monitors chloride changes to predict and confirm ovulation with 98.3% efficacy and giving 5-7 days notice of ovulation can be used for both irregular cycles and PCOS.
Research in to the efficacy of Ovacue concludes that it is able to effectively predict the fertile period but with ‘some degree of variation in predicting and detecting ovulation’ (Fehring 1996).
Ovacue’s customer support consists of FAQ’s, telephone and email support.
Cost – $269
Delivery – Dispatched same day
My opinion –
Ovacue offers an alternative to body temperature monitoring by measuring chloride. Chloride rises early in a normal cycle, but it does so with unpredictable timing, meaning that Ovacue works well for some women but not for others.
15. Ovatemp and ONDO
Ovatemp is an app that is used with the ONDO oral thermometer to monitor your basal body temperature with a single daily measurement. The app also allows you to track other physiological symptoms such as cervical mucus and the position of your cervix to identify fertile days. The website makes no reference to accuracy, it’s ability to predict or confirm ovulation, or whether it is suitable for irregular cycles and PCOS.
Ovatemp’s customer support is limited, with only FAQ’s available for technical assistance.
Cost – Free App. ONDO out of stock. No price point given.
Delivery – Not stated.
My opinion –
Similar to Kindara and Daysy, you are essentially paying for an oral thermometer and app to record your physiological signs and symptoms.
OvuSense is a vaginal sensor that syncs to a smartphone app. Unlike other temperature recording fertility monitors, OvuSense observes core body temperature by measuring in the vagina while you are asleep. The remote vaginal sensor takes multiple readings throughout the night. OvuSense is able to predict ovulation up to 24 hours in advance, correct 96% of the time, and it detects the exact date ovulation with 99% accuracy (Papaioannou et al. 2012 ESHRE; 2012 ASRM; 2013 ASRM; 2014 ESHRE).
OvuSense is suitable for any woman wishing to conceive and can be used by those women who have irregular cycles or ovulatory issues such as Polycystic Ovaries, PCOS or diminished ovarian reserve.
OvuSense offers 24 hour, 7 days a week technical support by email (firstname.lastname@example.org) and on phone call back, and fertility nurse 1:1 consultations via Skype or telephone. OvuSense also features an online community with regular online fertility clinics.
Cost – 99 or $299 options (starter pack including a 30-day subscription or 12-month subscription) – see their website for full details. www.ovusense.com
Use code DIVA2020 for 20% off.
My opinion –
OvuSense is the only fertility monitor that has the ability to predict ovulation in real time in the cycle – and this is because takes multiple readings of core body temperature in the vagina. The monthly plan offers the ability to cancel at any time which means you’re not locked in if you get pregnant or find it doesn’t work for you. Additionally, you can purchase a “one off” 12-month subscription and save money (however months not used if you get pregnant are not refunded). OvuSense support has been well received online.
Tempdrop is a sensor that uses skin temperature measurements to determine your personal nightly temperature and use this information to track ovulation and determine the most fertile days in a cycle.
Tempdrop is worn under your arm during sleep using the Tempdrop armband. Each night, Tempdrop collects thousands of data points on your body temperature and sleep motion and then in the morning syncs with the Tempdrop app.
Tempdrops support is limited and consists of FAQ’s on their website and app and an in-app chat service.
Cost – $149-249. Free App
Delivery – 4-6 weeks
My opinion –
It is unclear from the website if Tempdrop has been tested to accurately identify ovulation or the fertile time. Tempdrop quote a study by Rubia-Rubia et al. (2011) where the efficacy of skin temperature recording was compared to other methods. Skin temperature recordings were not found to be as accurate in measuring body temperature than other methods, but it was found to be convenient, easy to use and comfortable. Due to the inaccuracies of skin temperature monitoring, this is not a method I would recommend.
Yono is an in-ear fertility monitor and app. Yono monitors your basal body temperature overnight whilst you sleep using a small ear bud. There is little clinical research in to the efficacy of the tympanic (in-ear) route of temperature measurement for fertility. A recent study by Niven et al. (2015) concluded that peripheral thermometers ‘do not have clinically acceptable accuracy’ and should not be used when accuracy is important.
The website states that Yono can be used for ovulation prediction and that it identify the fertile days each cycle. There is no reference to accuracy or if the monitor can be used for women with irregular cycles or PCOS. Yono offers email support only.
Cost – Prices vary by style. Check their website.
Delivery – 4-8 weeks after ordering
Note from Amy: For more on this topic, listen to my podcast: The Best Ovulation Predictor Kit & Fertility Monitoring for PCOS
Kate works with women wishing to optimize their ability to conceive naturally and coaches women going through a difficult fertility journey. Kate is a registered nurse specialist and worked for over 20 years in the UK’s National Health Service as a specialist nurse in Gynecology, Sexual and contraceptive health and fertility. Kate, frustrated with the lack of support and high-quality advice for women who were struggling to conceive, founded her private practice ‘Your Fertility Journey’. Shortly after this, she trained as a fertility coach to offer her patients much needed emotional support as well as medical advice. Kate now has a thriving practice and consults women nationally and internationally via Skype. Kate has a special interest in PCOS and over the years has worked with 100’s of women who suffer with this debilitating condition. To enhance her practice, Kate has also undertaken specialist training to enable her to offer women both the specialist advice and emotional support they desperately need.
Facebook Support Group: https://www.facebook.com/groups/Yourfertilitysupportgroup/
My Favorite PCOS Fertility Tool [Podcast]
OvuSense- PCOS Fertility/Ovulation Monitor Update
Ovusense: Fertility Monitor for Women with PCOS [Updated]
The Best Ovulation Predictor Kit & Fertility Monitoring for PCOS [Podcast]
American Society for Reproductive Medicine (ASRM) (2012) Diagnostic evaluation of the infertile female. Fertil Steril 98: 2 302–307.
American Society for Reproductive Medicine (ASRM) (2013) Optimizing natural fertility. Fertil Steril 100:631-7.
Avawomen Ava for med prof 1. Available at: http://www.avawomen.com/wp-content/uploads/2016/07/Ava_for_med_prof-1.pdf (Accessed: 23 August 2016).
Baird, D.D., McConnaughey, D.R., Weinberg, C.R., Musey, P.L., Collins, D.C., Kesner, J.S., Knecht, E.A. and Wilcox, A.J. (1995) ‘Application of a method for estimating day of ovulation using urinary estrogen and Progesterone metabolites’, Epidemiology, 6(5), pp. 547–550. doi: 10.1097/00001648-199509000-00015.
Coyne MD, Kesick CM (2000) Circadian rhythm changes in core temperature over the menstrual cycle: method for noninvasive monitoring. Am J Physiol Regul Integr Comp Physiol 279:R1316-R1320
Duane, M., Contreras, A., Jensen, E.T. and White, A. (2016) ‘The performance of fertility awareness-based method Apps marketed to avoid pregnancy’, The Journal of the American Board of Family Medicine, 29(4), pp. 508–511. doi: 10.3122/jabfm.2016.04.160022.
ESHRE (2014). ART Fact Sheet. European Society for Human Reproductive Endocrinology. July 2014.https://www.eshre.eu/guidelines-and-legal/art-fact-sheet.aspx
Fehring, R.J. (1996) ‘A comparison of the ovulation method with the CUE ovulation predictor in determining the fertile period’, Journal of the American Academy of Nurse Practitioners, 8(10), pp. 461–466. doi: 10.1111/j.1745-7599.1996.tb00604.x.
Freundl, G. and Godehardt, E. (2003) ‘Estimated maximum failure rates of cycle monitors using daily conception probabilities in the menstrual cycle’, Human Reproduction, 18(12), pp. 2628–2633. doi: 10.1093/humrep/deg488.
Lenton EA, Landgren BM (1984 a) Normal variation in the length of the luteal phase of the menstrual cycle: identification of the short luteal phase. Br J Obstet Gynaecol 91:685-9.
Lenton EA, Landgren BM (1984 b) Normal variation in the length of the follicular phase of the menstrual cycle: effect of chronological age. Br J Obstet Gynaecol 91:681-4.
Niven, D.J., Gaudet, J.E., Laupland, K.B., Mrklas, K.J., Roberts, D.J. and Stelfox, H.T. (2015) ‘Accuracy of peripheral thermometers for estimating temperature’, Annals of Internal Medicine, 163(10), p. 768. doi: 10.7326/m15-1150.
Papaioannou S, Delkos D, Pardey J (2014) Vaginal core body temperature assessment identifies pre-ovulatory body temperature rise and detects ovulation in advance of ultrasound folliculometry. European Society of Human Reproduction and Embryology 30th Annual Conference.
Papaioannou S, Aslam M (2013) Quality Index assessment of vaginal temperature based fertility prediction and comparison with LH testing, ultrasound folliculometry and other home cycle monitors. American Society for Reproductive Medicine 69th Annual conference.
Papaioannou S, Aslam M (2013) User’s acceptability of Ovusense: a novel vaginal temperature sensor for prediction of the fertile period. J Obstet Gynaecol 33:705–9.
Papaioannou S, Aslam M (2012) Ovulation assessment by vaginal temperature analysis (Ovusense Fertility Monitoring System) in comparison to oral temperature recording. American Society for Reproductive Medicine 68th Annual conference.
Papaioannou S, Aslam M (2012) Ovulation Assessment and Fertile Period Prediction by Portable Computerised Vaginal Temperature Analysis – The OvuSense Advanced Fertility Monitoring System. European Society of Human Reproduction and Embryology 28th Annual Conference.
Rollason, J., Outtrim, J. and Mathur, R. (2014) ‘A pilot study comparing the DuoFertility® monitor with ultrasound in infertile women’, International Journal of Women’s Health, , p. 657. doi: 10.2147/ijwh.s59080.
Setton, R., Tierney, C. and Tsai, T. (2016) ‘The accuracy of web sites and cellular phone applications in predicting the fertile window’, Obstetrics & Gynecology, 128(1), pp. 58–63. doi: 10.1097/aog.0000000000001341.
Wark, J.D., Henningham, L., Gorelik, A., Jayasinghe, Y., Hartley, S. and Garland, S.M. (2015) ‘Basal temperature measurement using a multi-sensor Armband in Australian Young Women: A comparative observational study’, JMIR mHealth and uHealth, 3(4), p. e94. doi: 10.2196/mhealth.4263.
Wilcox, A.J., Weinberg, C.R. and Baird, D.D. (1995) ‘Timing of sexual intercourse in relation to ovulation — effects on the probability of conception, survival of the pregnancy, and sex of the baby’, New England Journal of Medicine, 333(23), pp. 1517–1521. doi: 10.1056/nejm199512073332301.
Wise, L.A., Hatch, E.E., Stanford, J., McKinnon, C.J., Wesselink, A. and Rothman, K.J. (2015) ‘A randomized trial of web-based fertility-tracking software and fecundability’, Fertility and Sterility, 104(3), p. e113. doi: 10.1016/j.fertnstert.2015.07.349.