The FDA has cleared an updated algorithm for Natural Cycles’ birth control app, marking its sixth regulatory approval in eight years. The new version combines machine learning with statistical modeling to generate more tailored fertility predictions, as stated in a July 27, 2026 announcement.
The updated NC° Fertility Algorithm keeps the app’s safety and effectiveness while increasing the number of “Green Days”—days when users are informed they don’t need additional contraception. The company reports effectiveness rates of 98% with perfect use and 93% with typical use, matching those of combined oral contraceptive pills, with figures supported by peer-reviewed clinical research and real-world evidence.
Algorithm improvements target irregular cycles and data quality
The update aims to improve performance for users with irregular menstrual cycles and better handle lower-quality temperature or biomarker data. It also adapts more quickly as a user’s cycle changes over time.
“The next chapter for digital contraception is making it more personalized and easier to use while keeping the same high standard of safety,” said Kerry Krauss, MD, senior medical advisor at Natural Cycles. She noted that the clearance shows how AI and machine learning can enhance the user experience without sacrificing scientific standards expected of a regulated medical device.
Natural Cycles has filed a patent application for parts of the updated algorithm. Its regulatory history includes clearances for integrations with the Oura Ring, Apple Watch, and its own wearable, the NC° Band. A 2024 Predetermined Change Control Plan (PCCP) clearance created a pathway for future hardware updates, including a Garmin integration released in March 2026.
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Regulatory pathway reflects growing acceptance of digital contraception
The FDA’s repeated clearances for Natural Cycles show a broader change in how regulators view digital health tools. The app was first cleared in 2018 through the De Novo pathway, designed for novel devices without existing equivalents. Later approvals, including the 2024 PCCP, simplified the process for future updates, reducing the need for full resubmissions.
The company has also secured authorizations in more than eight international markets, including Europe, Canada, Brazil, Australia, South Korea, and Singapore. In 2025, the FDA permitted the app to be sold both over-the-counter and by prescription.
Some healthcare providers remain skeptical. They argue that real-world effectiveness depends on user behavior and that digital contraception may not suit everyone. The company’s data shows a difference between perfect and typical use, highlighting that no method is entirely reliable.
Natural Cycles did not reveal how many users the updated algorithm will impact or when it will be available.
As digital health tools expand, policy breaches remain a concern for regulators and users alike.
