Wired for Wellness: Is Wearable Tech the future in fertility monitoring and general reproductive care?
By Sònia Gayete Lafuente, MD, PhD, who is a Foundation for Reproductive Medicine Research Fellow at the CHR. She can be reached through the editorial office of the VOICE.
Briefing: In recent years, wearable technology has transformed the landscape of personal health and fitness management. Devices such as smartwatches, fitness bands, and sensor-enabled clothing are now commonplace, offering unprecedented access to real-time data on metrics like heart rate, activity levels, and sleep quality. These advancements shaped as fashionable smart accessories and jewelry have empowered users to monitor physiologic responses in different scenarios and take a more proactive approach to their health. In social settings where healthy lifestyle, wellness, and preventative selfcare have become popular, wearable devices have attracted great interest and demand and are partnering with luxury fashion houses and highest-end fitness clubs, while advertised by celebrities and social media influencers. But what’s the science behind it?
The evolution of Smart Wearable Devices from fitness to specialized health
Beyond applications in general fitness, wearable devices are rapidly expanding into specialized health domains, including chronic disease management, mental health monitoring, and even early inflammatory disease detection. In fact, with advancements in their miniaturized sensors, wearables have moved from simple step counters to very sophisticated tools deemed capable of tracking complex processes such as ovarian cycles. In the fertility field, ovulation and menstrual cycle monitoring stand out as significant promising practical solutions for individuals as well as healthcare providers in gynecology. Their accuracy and reliability compared to standard methods are, however, still debatable. Therefore, this article aims to explore the current state of wearable devices in gynecology and fertility health and further aims to address the broader implications of integrating these technologies into personalized care.
The Rise of Wearable Devices in Fertility and Cycle Tracking
Current applications
Wearable devices are being increasingly used to track various physiological parameters relevant to fertility health. Some of the key tools include:
(i) Basal Body Temperature (BBT) Tracking: monitoring BBT can help identify ovulation and, therefore, the so-called fertile window and, with it, chances of conception.
(ii) Menstrual Cycle Tracking: Wearable devices can also track menstrual cycles based on mathematical algorithms, including data from the user’s menstrual calendar and bleeding patterns, along with BBT. This information can be used to identify irregularities and help predict upcoming ovulations and, thereby, optimize fertility.
(iii) Direct and Indirect Hormone Level Monitoring: Some wearable devices can infer hormone levels, such as estrogen and progesterone, which reflect ovarian function and play a crucial role in fertility and reproductive health.
Progesterone and estrogen levels are indirectly inferred by monitoring physiological changes associated with hormonal fluctuations. The key surrogate parameters include: BBT (which increases slightly after ovulation in response to progesterone rise), heart rate and its variability (since estrogen and progesterone influence the autonomic nervous system, affecting these cardiac parameters during different menstrual phases), respiratory rate (given that progesterone can increase respiratory rate, which some wearables detect as a marker of luteal phase), and skin conductance or electrodermal activity (since sweat gland activity, indirectly measurable through skin conductance, may be influenced by estrogen). Studies suggest that devices incorporating direct hormone level measurements from urine sensors are often more accurate while remaining user-friendly.
(iv) Cervical mucus electrical impedance: Newer intravaginal fertility tracking devices utilize vaginal electrolyte-based sensors, which provide useful insights into ovulation but still lack robust validation, claiming a sensitivity of 65% and specificity of 80% at its best. The Kegg device is the main one commercially available, detecting significant changes in the cervical mucus electrical impedance between the different menstrual cycle phases.
Reliability and Accuracy
While wearable devices have shown significant promise in gynecology and fertility tracking, their reliability is still a crucial factor to consider. Several studies have evaluated the accuracy of wearable devices in tracking fertility-related parameters. A recent extensive narrative review identified 23 commercially available, nonprescription wearables in the U.S. that help track the fertile window by utilizing parameters like BBT or urinary hormone levels. These devices, worn on the wrist, fingers, intravaginally, or inside the ear, demonstrate high accuracy in detecting various stages of the menstrual cycle, including the luteal phase, fertile window (generally with an accepted error of +/- 1 to 1.5 days), and menstruation.
Amongst the most reliable devices is the Ava Fertility Tracker (top photo). It is a bracelet worn during sleep which monitors multiple physiological signals to predict ovulation and to identify the fertile window, and was in 2021 the first to receive FDA 510(k) clearance, thereby becoming the first machine learning device approved to aid women in ovulation prediction. This was also followed that same year by the Ava bracelet, the popular Oura ring integrated with the Natural Cycle app (middle photo), also FDA-approved. Although the Oura ring is not in itself cleared by the FDA for fertility tracking, its integration with the approved birth control app Natural Cycles allows for enhanced fertility tracking capabilities. In fact, multiple commercial integrations of wearable devices have been recently launched with the aim of increasing the accuracy of fertility tracking, among those the Kegg plus Mira device (bottom photo), another popular example that combines data from cervical mucus impedance and urine hormone levels.
All of these devices represent significant progress in the use of digital non-invasive methods for fertility tracking. However, significant challenges remain. Research evaluating the accuracy and reliability of these technologies is limited, and the few available studies often lack standardized validations. Moreover, factors such as device calibration, user compliance, and individual variability among others can impact the accuracy of their measurements.
Current Trends and Practical Challenges
The market for technology aimed at tracking ovulation to support conception is rapidly expanding in the U.S., attracting the increasingly tech-smart reproductive-age female population. The million-dollar question for wearable fertility trackers is whether these devices could one day replace traditional cycle monitoring in Assisted Reproductive Technologies (ART). Imagine a system where real-time hormone levels, captured non-invasively by a patient’s wearable device, are seamlessly shared with healthcare providers through electronic medical records or patient platforms in real-time. This would allow the monitoring if intrauterine insemination or in vitro fertilization (IVF) cycles remotely, or would permit embryo transfer timing and/or other treatment adjustments without so frequent clinic visits. Such innovations are already hinted at by systems like Oova, which use at-home LH and progesterone urine tests (now integrated with a BBT-tracker bracelet) to send results via digital platforms.
Expanding on this concept, wearable devices might take remote cycle monitoring to the next level, offering continuous, non-invasive data collection that could revolutionize how fertility treatments are managed. However, realizing this vision will require significant advancements in technology. Moreover, the infertility field has seen already too many insufficient validations of new “add-ons” to infertility practice and must make sure through rigorous studies that this will not happen again here. In addition to the somewhat-limited reliability compared to direct blood hormone measurements, other practical challenges must also be overcome. For example, careful ethical considerations come up regarding privacy and security of digital health data. Finally, the high cost of many of these devices poses an accessibility barrier, highlighting the need for more cost-effective solutions to reach broader consumer access.
Future Directions and Implications
As the technology continues to evolve, we can expect to see more sophisticated devices that empower women with valuable insights into their reproductive health. For now, however, their use should be limited to the simplest stages. Expectations expressed by industry have been that wearable devices could help reduce healthcare costs by enabling women to track their fertility treatment cycles remotely, thereby reducing the need for clinic visits and laboratory tests. Considering the history of reproductive medicine, we, however, remain skeptical because we are still waiting for an “add-on” to IVF that has lowered IVF costs. The opposite has, indeed, always been the case.
Let’s see where the science takes us. For now, still only one cycle at a time!
Reading List
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