Wearables use AI and temp dips to reveal cycle timing

None of these devices measures hormones directly. Instead, they track the knock-on effects. After ovulation, the hormone progesterone nudges your resting body temperature up slightly, and it stays higher until your period. A ring or band worn overnight can catch that shift, then combine it with your resting heart rate, heart rate variability and the symptoms and dates you log yourself.

Software then turns those signals into a forecast: a window for your next period, a likely fertile window, and in some cases a confirmation that ovulation already happened. The more months you wear it, the more the model adjusts to you.

Ultrahuman’s Cycle and Ovulation Pro is a paid add-on for its Ring Air. The company says it confirms ovulation with more than 90% accuracy, which it based on testing against a method that tracks rises in luteinizing hormone and progesterone. The algorithm came from viO HealthTech, which Ultrahuman bought. It was originally built for an internal fertility monitor and draws on data from more than 260,000 cycles, backed by 15 years of research and 13 peer-reviewed studies.

The Pro version also raises Cycle Flags, which point out patterns like late, early or missing ovulation and a short luteal phase (the stretch between ovulation and your period). It costs $3.99 a month or $39.99 a year and is sold in the US, Canada, the UK, the EU and Australia. A basic cycle tracker stays free.

The catch: the original algorithm is FDA-cleared for internal use, but the ring version is a wellness tool and is not. Ultrahuman is clear that it is not a form of contraception. Oura, for its part, claims 96.4% for its own ovulation confirmation, but the two companies tested in different ways, so the figures do not compare cleanly.

Oura has leaned furthest into later life stages. Starting May 6, it rolled out Menopause Insights worldwide, built around its own Menopause Impact Scale, a questionnaire that measures how much symptoms disrupt your daily life. A personal dashboard then lines those answers up against the ring’s sleep and temperature data over time.

The same update added Hormonal Birth Control support. You can log the method you use, whether that is an implant, an IUD, a patch or the pill, and see how it affects your temperature, sleep and recovery. In the US, Oura works with Twentyeight Health to offer virtual consultations and prescriptions for contraception. Oura also offers an AI model trained to answer women’s health questions.

Apple took a lighter approach. Cycle Tracking in the Health app has logged periods and symptoms for years, and with watchOS 27 it gained perimenopause and menopause support. The Health app can now flag when your logged cycles suggest possible perimenopause, with symptom logging and background reading to go with it. There is no subscription on top of the watch itself.

Whoop’s Hormonal Symptom Insights and Predictions builds a model of your cycle from skin temperature, resting heart rate and heart rate variability, plus what you log. It shows a date window for your next period, when symptoms are likely, and trends in cycle length and variability.

Where Whoop stands out is blood work. Its Advanced Labs service tests 65 biomarkers, and a US-only Women’s Health panel adds 11 more, covering things like progesterone, prolactin, thyroid markers and anti-müllerian hormone (a rough guide to egg count). The panel costs $299 on top of a membership, with blood drawn at Quest Diagnostics. Results are shown against where you are in your cycle.

In August, Whoop also connected with Natural Cycles, the only FDA-cleared app for hormone-free birth control. Compatible bands can send overnight skin temperature straight to the app, and new Natural Cycles users get the first year included with their Whoop membership. Whoop memberships run from $199 to $359 a year.

If you are shopping for a cycle or menopause tracker, start with these questions:

• Is any part of it medically cleared? Only Natural Cycles, used with a compatible device, is FDA-cleared for birth control here. Everything else is a wellness estimate.
• Does it cope with irregular cycles? Look for tools that learn your pattern rather than assuming 28 days, especially if you have PCOS or are in perimenopause.
• Does it cover menopause? Oura and Apple now have dedicated perimenopause and menopause tools, and Natural Cycles has a perimenopause mode.
• What is the true monthly cost? Add the device, the membership and any add-ons. Apple’s tools come with the watch, Ultrahuman’s Pro add-on is $3.99 a month, and Whoop’s lab panel is extra.
• Will you wear it at night? Temperature tracking only works if you sleep in it, which is easier with a ring than a watch for many people.
• Can you share the data with your doctor? Oura lets you share reports with healthcare providers, which makes the numbers more useful in an appointment.

For most people, the best wearable is the one already on your hand. If you own an Apple Watch, the new perimenopause alerts cost nothing extra. If you want ovulation confirmation for planning a pregnancy, Ultrahuman’s paid add-on or Oura’s tools go further. If you like lab numbers, Whoop’s blood panel gives you hard data, at a price and only in the US.

Treat every reading as a clue, not a diagnosis. These devices can help you notice a change and start a better conversation with your doctor. They cannot rule out a condition, and outside the one FDA-cleared app, none should be your birth control.