- We recorded over 60 cycle-starts from 22 users. Filtering for consistent ring use and OPK adherence, we recorded 48 complete cycles over the course of the study.
- We expectedly obtained a mix of ovulatory and anovulatory cycles. Some cycles also had no clear hormonal trend hence no LH surge event could be recorded.
- Calendar method vs Ultrahuman algorithm had a median difference of 2 days across all cycles.
- In the 22 cycles for which we had continuous ring use, OPKs verified a distinct LH surge to mark the cycles’ follicular and luteal phases. Comparing these cycles, we found a median difference of 1 day between the Ultrahuman algorithm and hormonal test result of peak LH levels. Figure 1 below shows the overlap of prediction events by the Ultrahuman algorithm with those by the Inito app (left) and by the calendar method (right).
- In 16 cycles, the Inito OPK test registered a positive ovulation event. These were cycles wherein not only a reliable LH surge had occurred, but also the latter of the biphasic rise of estrogen and then progesterone measured by PdG were recorded post the LH surge. These cycles had the same 1 day median difference with the Ultrahuman algorithm.
- In women with variable cycles or older women reporting menopause transition, the median difference between the Ultrahuman algorithm and the hormonal test increased to 5 days, as we found several LH surge events recorded from the Inito test and fluctuating cadence of biomarkers captured by the ring. No confirmed ovulation prediction was provided by the OPK in these cases.
Figure 1: Radar plots showing overlap and differences at the level of individual cycles between prediction difference of LH surge by Ultrahuman cycle tracking algorithm as compared to hormonal method (left) and calendar method (right). Extent of deviations (in days) are shown as concentric circles, while the area under the polygon depicts the zone of difference per cycle compared. N = 22 cycles.
Discussion and Future Development
Modern day insights into women’s health can benefit a great deal from continuous data streams provided by at-home and wearable devices12. In the short term, the insights can help optimize training by identifying peak performance windows or certain phases that may have minimal difference on the choice of fitness regime on an individual’s body. In the long term, continuous tracking allows for the detection of cycle irregularities or anomalies, offering an opportunity to catch early signs of conditions like PCOS, thyroid issues, or other hormonal imbalances.
Several life-altering physiological events, which cause large changes in metabolism, mental health and fitness, are increasingly being found to meld into each other rather than have discrete start and end points. For example, a healthy woman in her 30s may consider based on her family history that her fertility reserve would last another ten years. However, modern day stressors and diet quality may change her physiology substantially to advance her transition into perimenopause. Continuous cycle tracking can pick up early trends faster not just in terms of cycle length but also in baseline HR, HRV and sleep. Currently women health support is divided rather arbitrarily into fertile/pregnancy and menopause transition stages. Different apps and devices provide support for one or the other, but devices such as the Ultrahuman Ring AIR can provide the continuous bridge data to help navigate life stages.
To register cycle mid-point we chose to monitor an event that is tracked by several applications, namely the LH surge. This hormonal event is followed by release of the egg and is usually central to planning conception or contraception as per needs. LH surges become more sporadic with aging as well as in women with irregular periods. LH surge occurs across a multi-hour window and can span over datelines (12 midnight). Therefore, the recorded 1-day difference between Ultrahuman algorithm and hormonal testing could actually be tracking the same event rather than another at a delay of a day. The calendar method expectedly did have more deviations from the biomarker based method since it is a rigid algorithm without room for changes in cycle length. In older participants and those with irregular cycles, there was less overlap in LH surge detection due to several deviations in continuous biomarkers and multiple small spikes of LH hormone. This is in concordance with known lower prediction overlaps for irregular menstruators13. Taken together, women with consistent cycles in this pilot were able to determine that the Ultrahuman algorithm is reasonably accurate in tracking LH surge as compared to at-home OPK approach.
While easy to use and near continuous, it is to be acknowledged that physiological readouts can be impacted by infection and other disease conditions and hence their accuracy can be compromised2. Severe viral infections or chronic metabolic conditions have been known to shift cycles and cause hormonal imbalance14, 15. Hence non-invasive tracking can’t be a stand alone proxy for conception or contraception goals. Ultrahuman’s approach to women's health is to be a partner through various stages of their health journey. This ‘Cycle and Ovulation’ power plug will be released without a subscription fee globally, integrating the tracking device and the algorithm on the same platform.
Reach out to partnerships@ultrahuman.com for commercial queries and science@ultrahuman.com for scientific queries.
