Key takeaways
- NC° Birth Control is equally effective when used with a wearable or thermometer to measure temperature data: 98% when used as intended and 93% with typical use
- Those measuring with a wearable add more temperature data and get more Green Days on average compared to those using an oral thermometer
- Wearable users are more likely to continue using NC° Birth Control after one year (compared to thermometer users), highlighting the importance of having a convenient way of measuring
Traditionally, methods using basal body temperature to track the menstrual cycle have relied on measuring orally with a basal thermometer. The same was true for the digital birth control Natural Cycles: users measured their basal body temperature upon waking up in the morning, logged the temperature in the Natural Cycles app, and the algorithm calculated their daily fertility status.
In the last few years, wearable technology has enabled a whole new measuring experience and brought real change for those using the Natural Cycles app, too. Users can now wear a compatible wearable device to bed to measure overnight, and then simply sync their temperature in the morning to get their daily fertility status. This has allowed for a smoother and more seamless experience when using digital birth control.
Why did we do this study?
Given that Natural Cycles is a relatively new birth control method — the first and only FDA-cleared and CE-marked birth control app on the market — we frequently get questions around how measuring habits may impact its effectiveness.
Natural Cycles’ effectiveness as a birth control method has been demonstrated in several previous studies. Now, the NC° Research Team set out to compare whether the effectiveness differed between those measuring with an oral thermometer and those measuring with a wearable.
Additionally, they were interested in whether the choice of measuring device affected how long users stayed with Natural Cycles.
What were the results?
The team analyzed cycles from 83,000 users who measured with a wearable and 125,000 users who measured orally with a thermometer — a total of 1,566,000 cycles. Each user participated in the study for up to 1 year or 13 cycles (whichever happened first).
Wearable users in the study had slightly fewer pregnancies than thermometer users, but they were also a different group of people on average (for example, more likely to abstain on fertile days). Once we compared like-for-like users, the results showed that Natural Cycles’ effectiveness was the same regardless of how users choose to measure temperature: 98% when used as intended (which means using protection or abstaining from vaginal sex on Red Days), and 93% with typical use.
However, while effectiveness stayed the same, the results showed another interesting finding. Users who measured with a wearable were more likely to continue using the method for longer. 76% of those who measured with a wearable were still using Natural Cycles after one full year, compared to 56% of those who measured with a thermometer.
Additionally, wearable users added temperature data on 82% of days, compared to thermometer users who added data on 56% of days. While this doesn’t change the effectiveness of Natural Cycles, more data allow the NC° Fertility Algorithm to narrow down the fertile days, resulting in 10% more Green Days on average (days when no protection is needed).
Why does this research matter?
This finding highlights something very important: convenience matters when it comes to birth control choice — a method will only work if you keep using it. And ease of use plays an important role in this! Wearables take away the need to measure manually, creating a more seamless experience.
Natural Cycles is compatible with several wearables, so you can choose the one that best suits your routine without compromising effectiveness.
