A regulated contraceptive, not just a digital diary
In a country where millions of women already use unregulated cycle-tracking apps without knowing the difference, Brazil has quietly crossed a threshold: for the first time, a digital tool has been granted the same regulatory standing as a pharmaceutical contraceptive. Natural Cycles, born from a physicist's search for a hormone-free alternative, arrives in Brazil not merely as an app but as a certified medical device — one that listens to each woman's body rather than applying a universal formula. The deeper question it raises is not whether algorithms can prevent pregnancy, but whether a society is ready to trust data with something as intimate as reproductive choice.
- For the first time, Brazil's health regulator Anvisa has certified a digital app as a contraceptive medical device, drawing a sharp legal and scientific line between validated technology and the flood of unregulated period-tracking tools already on millions of phones.
- The stakes are high: women who confuse ordinary cycle-logging apps with actual contraception face real pregnancy risk, making public education as urgent as the regulatory approval itself.
- Natural Cycles counters this confusion with clinical weight — studies across sixty thousand women, FDA and CE Mark certifications, and efficacy rates that match the birth control pill in everyday use at ninety-three percent.
- The app's algorithm learns from each individual's basal body temperature readings rather than applying a fixed formula, representing a meaningful departure from the discredited rhythm method it is often mistaken for.
- Launched at Brazil's premier gynecology congress in Belo Horizonte, the technology is being introduced directly to the medical community whose trust will determine whether patients adopt it as a legitimate, hormone-free alternative.
- The path forward runs through conversation — between doctors and patients, between data science and clinical culture — in a country where that dialogue around digital contraception is only just beginning.
Brazil has approved its first regulated digital contraceptive, marking the country's entry into a new category of hormone-free birth control. The app, Natural Cycles, launches with Anvisa certification and the backing of Brazil's leading obstetrics and gynecology federation, and is being presented this week at the 63rd Brazilian Congress of Gynecology and Obstetrics in Belo Horizonte.
The distinction between this app and the dozens of unregulated period-tracking tools already on the market is not cosmetic — it is clinical. Most menstrual apps are digital diaries with no scientific validation and no contraceptive function. Natural Cycles is a tested medical device, adapted fully for Brazil with a Portuguese interface, real-denominated payments, and availability to women eighteen and older.
Each morning, a user measures her basal body temperature upon waking, using a thermometer or a connected wearable. The app's algorithm processes these readings alongside cycle data to assign a daily fertility risk: red for fertile days requiring condoms, green for days safe for unprotected sex. Unlike the old rhythm method, the algorithm is individualized — it learns from each woman's own body signals rather than applying a universal formula.
Efficacy data drawn from over sixty thousand women shows ninety-eight percent effectiveness under perfect use and ninety-three percent in typical use — figures that mirror what most women actually experience with the birth control pill once missed doses and real-life variables are factored in. The platform, founded in 2013 by physicists Elina Berglund Scherwitzl and Raoul Scherwitzl, now monitors more than twenty million cycles across six million users in over thirty countries, carrying both FDA and CE Mark certification.
Data privacy is handled through encryption and pseudonymization. But the company's country manager, Taurã Figueiredo, identifies the real challenge ahead as neither technical nor regulatory — it is one of trust. Brazil must now build the clinical and public understanding needed to distinguish a validated digital contraceptive from the unregulated apps already downloaded millions of times. That conversation is only beginning.
Brazil has just approved its first regulated digital contraceptive, a shift that marks the country's entry into a new category of hormone-free birth control. The app, called Natural Cycles, launches officially next week with the blessing of Anvisa, the national health regulator, and the support of Brazil's leading obstetrics and gynecology federation. The technology is being presented this week at the 63rd Brazilian Congress of Gynecology and Obstetrics in Belo Horizonte, where doctors and specialists are learning how it works and what sets it apart from the dozens of unregulated period-tracking apps already on the market.
The distinction matters enormously. Most menstrual-tracking apps are simply digital diaries—they log dates and patterns but have no scientific validation and cannot prevent pregnancy. Natural Cycles is different. It is a medical device, tested in laboratories, approved by health authorities, and designed specifically to work as contraception. Until now, no app in Brazil held that status. The company adapted the platform entirely for the Brazilian market: the interface is in Portuguese, payments are in real, and it is available to women eighteen and older.
How it works is straightforward in principle but powered by sophisticated data analysis. Each morning, a user measures her basal body temperature—the temperature upon waking—using a compatible thermometer or a connected device like an Apple Watch, Oura Ring, or Garmin Watch. The app collects these readings along with information about her menstrual cycle and feeds them into an algorithm that calculates her fertility risk for each day. The screen shows red on fertile days, when pregnancy is possible and condoms are required if there is sexual contact. Green days are safe for unprotected sex. This is not the old rhythm method, which applied the same mathematical formula to every woman. The algorithm learns from each individual's body signals.
The efficacy data comes from studies involving more than sixty thousand women. In perfect use—when a woman follows every instruction without deviation—the app achieves ninety-eight percent effectiveness. In typical use, accounting for the small lapses and forgotten measurements that happen in real life, it reaches ninety-three percent. For context, the standard birth control pill achieves ninety-nine percent effectiveness in perfect laboratory conditions but also drops to roughly ninety-three percent in everyday use, when women miss doses, take other medications, or experience vomiting or diarrhea. The app's performance matches what most women actually experience with pills.
The technology originated in 2013 when physicist Elina Berglund Scherwitzl, searching for a contraceptive method that was neither hormonal nor invasive, partnered with physicist Raoul Scherwitzl to build a data-science solution. Today the platform monitors more than twenty million cycles across six million users in more than thirty countries. The algorithm carries certification from the FDA in the United States and the CE Mark in Europe. In Brazil, Anvisa granted approval in March 2025.
Because the app handles intimate health information, security protocols are strict. The system uses encryption and pseudonimization—a technique that obscures a user's real identity—to ensure that personal data remains protected. Taurã Figueiredo, the company's country manager in Brazil, frames the challenge ahead not as a technological one but as a matter of trust and understanding. The app is already validated internationally. What Brazil needs now is for doctors and patients to grasp what distinguishes a regulated digital contraceptive from the countless unregulated cycle-tracking tools already downloaded millions of times. That conversation is just beginning.
Citações Notáveis
When we talk about digital contraception, we're not just talking about technology, but about an important shift in how information, science, and autonomy reach clinical practice.— Taurã Figueiredo, country manager of Natural Cycles in Brazil
Success in Brazil will depend less on presenting a technological novelty and more on building correct understanding, message security, and clinical trust around an alternative that is already validated internationally.— Taurã Figueiredo, country manager of Natural Cycles in Brazil
A Conversa do Hearth Outra perspectiva sobre a história
Why does it matter that this is the first regulated contraceptive app in Brazil, rather than just another period-tracking tool?
Because most apps people download are essentially digital notebooks. They have no scientific testing, no approval from health authorities, and they cannot actually prevent pregnancy. Natural Cycles is a medical device—it was tested on sixty thousand women, approved by Anvisa, and designed specifically to work as contraception. That's a completely different category.
So the algorithm is reading the woman's body, not just applying a formula everyone uses?
Exactly. The old rhythm method used the same calculation for every woman. This app measures each person's basal temperature and learns her individual patterns. It's personalized data analysis, not a one-size-fits-all calendar.
The ninety-three percent effectiveness in typical use—how does that compare to what women actually experience with pills?
It's identical. Pills are ninety-nine percent effective in perfect conditions, but in real life they drop to ninety-three percent because people forget doses, take other medications, get sick. The app's ninety-three percent is already accounting for the small mistakes and lapses that actually happen.
Why would a woman choose this over a pill if the effectiveness is the same?
Because it's hormone-free, it's not invasive, and some women simply want to avoid the side effects that come with hormonal contraception. It also gives her direct control—she sees her own data, understands her own cycle, and makes daily decisions based on that information.
What's the real barrier to adoption in Brazil?
Not the technology itself. The app works and it's proven. The barrier is that doctors and patients need to understand what it actually is. There are hundreds of unregulated period apps out there, and people might confuse this with those. Building clinical trust and clear communication about what makes this different—that's the work ahead.