Natural Cycles receives sixth FDA clearance for fertility algorithm

Natural Cycles has received its sixth FDA clearance for an updated fertility algorithm designed to personalise digital contraception.

The regulator cleared the company’s next-generation NC° Fertility Algorithm, which combines statistical modelling with machine learning to predict fertile and non-fertile days.

Natural Cycles said the algorithm was trained on tens of millions of real-world fertility data points and adapts to individual cycle patterns.

“People don’t just want effective birth control; they want a method that fits naturally into their lives,” said Dr Elina Berglund Scherwitzl, chief executive and co-founder of Natural Cycles.

“One of the unique advantages of a software-based contraceptive is that it can continue to evolve.

“As our scientific understanding of fertility grows and we continue to learn from more than a decade of real-world data, we can responsibly refine the technology through rigorous research, clinical validation, and FDA review.

“This latest clearance is the result of that work, helping us give many users more flexibility while maintaining the effectiveness they rely on.”

Evidence supporting the FDA clearance showed that the updated system maintained the app’s established safety and effectiveness while giving many users more Green Days.

Green Days are those on which the app confirms that pregnancy protection is not needed.

The birth control app remains 98 per cent effective when used as intended and 93 per cent effective with typical use, according to the company.

Natural Cycles said these rates place it in the same effectiveness category as the combined oral contraceptive pill.

Typical use includes mistakes or inconsistent use, while intended use means following the method correctly.

Digital contraception uses technology and physiological data, such as body temperature, to provide personalised fertility predictions.

Natural Cycles said its updated algorithm can identify fertile and non-fertile days more precisely than traditional fertility awareness methods, which may classify larger parts of the cycle as potentially fertile.

The changes provide more Green Days while maintaining effectiveness, improve performance for people with irregular cycles and better handle lower-quality temperature or biomarker data, the company said.

A biomarker is a measurable biological signal, such as body temperature, that provides information about processes taking place in the body.

Natural Cycles also said the system can personalise its predictions more quickly as a user’s menstrual cycle changes over time.

“Years ago, the question was whether digital contraception could work. Today, Natural Cycles has demonstrated robust clinical and real-world evidence that it can,” said Dr Kerry Krauss, senior medical adviser at Natural Cycles.

“The next chapter for digital contraception is making it more personalised and easier to use while maintaining the same high standard of safety.

“This FDA clearance demonstrates how advances in AI and machine learning can improve the user experience while preserving the scientific rigour expected of a regulated medical device.”

Natural Cycles has filed a patent application covering key innovations in the updated algorithm.

The decision follows the FDA’s first De Novo clearance of the company’s birth control app in 2018.

Later clearances allowed the app to integrate with the Oura Ring in 2021 and Apple Watch in 2023.

In 2024, the FDA cleared a Predetermined Change Control Plan, creating a regulatory pathway for future hardware integrations.

Natural Cycles said the plan has since enabled the launch of its NC° Band and other hardware integrations, including a Garmin connection introduced in March 2026.

A further clearance in 2025 allowed the birth control app to be offered both over the counter and by prescription.

The company has also received regulatory authorisations in more than eight markets worldwide, including Europe, Canada, Brazil, Australia, South Korea and Singapore.