What Natural Cycles actually does
Natural Cycles is a birth control app built around a validated algorithm: each morning before getting out of bed, you take your basal body temperature with a dedicated thermometer (included with an annual plan, or a compatible Bluetooth thermometer) and log it in the app. The algorithm cross-references your temperature pattern with cycle history to classify each day as 'green' (no protection needed) or 'red' (fertile — use protection or abstain if you don't want to conceive).
Unlike most fertility or period apps, this isn't a soft wellness feature: Natural Cycles is registered as a genuine contraceptive medical device, which means its effectiveness claims are regulated and its marketing cannot overstate what the algorithm can do.
The company was founded in Stockholm in 2013 by Dr. Elina Berglund Scherwitzl, a particle physicist who had previously worked at CERN on research contributing to the discovery of the Higgs boson, together with her husband Raoul Scherwitzl; she built the underlying algorithm after looking for a reliable, hormone-free contraceptive method for her own use once she left physics research. Natural Cycles now reports serving more than 6 million users worldwide, a community it refers to internally as "Cyclers."
The core product
The app can be set to 'Birth Control' mode or 'Plan Pregnancy' mode, and it also layers general cycle and ovulation insights, mood and symptom logging, and integration with select wearables (some Bluetooth thermometers or wearables can auto-sync temperature instead of manual entry). The subscription is what unlocks the contraceptive algorithm itself — this is not a free app with a paid add-on, since the entire point of the product is the certified prediction engine.
What's new or notable
Natural Cycles has continued expanding its regulatory footprint, holding:
- FDA clearance — its original clearance, plus additional FDA clearances including for third-party wearable temperature integration
- A Health Canada Class II license
- Listings in Australia's ARTG and Singapore's SMDR
It also holds EN ISO 13485 quality-management certification, the standard specific to medical device manufacturing, which is not something typical period-tracking apps pursue since they don't need it.
Who should use Natural Cycles
Great fit if…
- You want to stop hormonal birth control but still need a reliable, trackable, non-permanent method and are willing to take your temperature every morning.
- You have a reasonably regular routine (consistent wake times, no major shift-work disruption) since basal temperature accuracy depends on measurement consistency.
- You value regulatory transparency — the app must disclose real effectiveness rates rather than marketing them as near-perfect, which is a direct consequence of its medical device status.
Skip it if…
- You need near-zero pregnancy risk — an IUD or implant will outperform the 93% typical-use effectiveness figure by a wide margin.
- Your schedule is unpredictable (frequent shift work, jet lag, illness) since inconsistent temperature readings directly degrade the algorithm's accuracy and increase red days.
Pricing in detail
Natural Cycles is subscription-only; there is no meaningful free tier since the certified algorithm is the entire product. European pricing (per a 2026 French-language review of the EU app) runs approximately €8.99/month or €64.99/year when billed annually — the annual plan includes a basal thermometer at no extra cost, while the thermometer sold standalone runs separately in each region's local currency. Pricing varies by country and currency; always check the localized signup page for your region before subscribing.
| Plan | Price | What's included |
|---|---|---|
| Monthly | ~€8.99/month | Full contraceptive algorithm, cycle tracking, app-only (no thermometer included) |
| Annual | ~€64.99/year | Same features plus a free NC° basal thermometer, lower effective monthly cost |
Where it falls short
- Real-world effectiveness depends heavily on user behavior — the headline 98% figure is 'perfect use' only; typical use sits at 93%, and the gap is filled by 'red days' requiring backup contraception.
- No STI protection — like any fertility-awareness method, it addresses pregnancy prevention only.
Privacy & data
The app collects daily temperature readings, cycle data, and optionally mood/symptom logs — categories that count as sensitive health data under GDPR. As a Sweden-headquartered company operating a certified medical device in the EU, Natural Cycles is subject to both GDPR and medical device post-market surveillance obligations, which require more rigorous data-handling documentation than a typical consumer wellness app.
How we checked this
Checked 2026-09-05 against Natural Cycles' own certifications page (help.naturalcycles.com) confirming FDA Class II clearance and CE0123 Class IIb marking, the company's signup flow (signup.naturalcycles.com), 2024 Series C funding announcements naming Lauxera Capital Partners, EQT Ventures and Bonnier Capital as investors, a 2026 French-language independent review for EUR subscription pricing, and Natural Cycles' own "About" page for founding history and current user figures.