Women Are Using Oura Rings as Part of Their Birth Control — But It’s Raising Concerns

There's no denying the popularity of the Oura Ring — over two and a half million of these little wearables have been sold worldwide, according to the company. In fact, the Gen3 model was named the best overall smart ring by our tech experts in the Good Housekeeping Institute.

For the uninitiated, the Oura is a health and fitness tracker — just slide it on your finger, and it monitors 20 specific biometrics that affect different aspects of your health. Fans say they love that the Oura Ring and its app deliver real-time data analysis, offering an up-to-the-second snapshot of how your body is functioning. For example, the Oura app provides "readiness" and "sleep" scores, which you can check first thing in the morning to assess the quality of your rest. Throughout the day, you can also monitor stress levels, track your activity to evaluate workout performance and identify optimal moments for a mindful break.

However, the latest trend in using the Oura Ring is stirring up some controversy: Some women are now turning to the fitness and sleep tracker to help with birth control. “A bunch of my friends have gotten Oura Rings and have stopped using birth control,” one GH staffer reported. “It's pretty concerning to me because I know they don't want babies right now.”

The trend is a big deal on TikTok and there is much discussion about it across social media. But is it a good idea? And does the Oura Ring actually work as birth control?

The answer is a bit complicated, but for many women the answer is no, and there are methods (including nonhormonal ones) with better success rates. The upshot is that the track record of the method women are using when they employ the Oura Ring as part of their birth control isn't great, even if it is much better than the same method practiced without the Oura Ring.

Oura partners with an outside app called Natural Cycles, which cites a 98% effectiveness rate at preventing pregnancy "with perfect use." This app, which is powered by the data Oura collects (it also works with Apple Watch and other devices), is FDA-cleared, meaning that it is similar to another FDA-approved product already on the market. Natural Cycles works by "analyzing body temperature and other key fertility indicators to determine your daily fertility status." Natural Cycles' website slogan is "Birth control built around you."

While it’s not known how many young women use the Oura combined with Natural Cycles as their sole form of contraception — or whether they were actually trying to conceive, rather than prevent pregnancy or are simply curious about their cycles — it is a popular feature: As of June 2024, 32% of Oura Ring users in their 30s and 43% in their 20s were connecting their devices with Natural Cycles, says Neta Gotlieb, Ph.D., a senior product manager for women’s health at Oura.

“Oura Ring is not intended to be used for birth control,” Gotlieb emphasizes. Oura merely "powers" (i.e., provides data for) the Natural Cycles app.

It works like this: People wear the ring to sleep, and during the night it measures body temperature, which varies slightly through a person's menstrual cycle. That data is then sent to the Natural Cycles app, which gives you a readout on your phone indicating your current level of fertility. If the app tells you it’s a “Green Day” according to your temperature, it indicates you aren’t fertile that day. If the app says it’s a “Red Day,” you definitely need to use protection if you have sex.

What does body temperature have to do with fertility? There are slight variations in your body temperature throughout your cycle. The rise in progesterone after ovulation, for example, raises temperature, and if you take your temperature, it will show as slightly higher around this time. The idea is that if you've just ovulated, it's a fertile period (although you may also be also fertile before this time.) “If you’re experiencing a surge in the luteinizing hormone, or LH, that’s when you’re most likely to get pregnant," says Susan Mitchell-Derenkski, APRN, WHNP-BC, a nurse practitioner and OB/GYN specialist at Washington University School of Medicine’s Contraceptive Choice Center in St. Louis.

The way Oura and Natural Cycles work together is essentially a new way to practice a fertility awareness-based method of birth control that has been around forever, and historically has not been very effective. “Basal body temperature measurements have been used for decades to help women optimize the timing of intercourse during a fertile window,” according to an article in the National Library of Medicine at the National Institutes of Health (NIH). “This unique methodology was also prevalent before the invention of oral contraception pills, as it aided women in an attempt to avoid fertilization during a fertile period.”

One difference between the way the Basal Body Temperature (BBT) method has been used by most women and is being used now with Oura Ring and Natural Cycles: Women have traditionally taken their temperature with an oral thermometer first thing in the morning and compared it to the previous days' measurements; this measures core (or basal) body temperature, or your temperature inside after a period of rest, rather than on the surface, as the ring on your finger does. One study found that measuring shell temperature throughout the night (as Oura Ring does) was slightly more sensitive than core temperature in detecting ovulation.

The best answer we have to that is, paired with the Natural Cycles app, it is pretty likely to be accurate — but that still does not mean that the body temperature method of birth control is very effective overall.

Let us explain: The ring itself does a great job measuring shell temperature, boasting a 99% lab accuracy rate and that using shell temperature instead of basal or core temperature provides more detail. Citing research, Oura says that shell temperature can even carry more information than core temperature due to the fact that your body serves as insulation. This means that your core temperature can only change in only a limited way. “Your shell exhibits frequent, and more significant, changes in your skin temperature, while core changes can be more muffled,” the website states.

Still, whether that extra detail helps pinpoint fertility is not clear. “Overnight tracking is not necessarily more accurate than morning temperature tracking, but it is a convenient way to measure temperature if you are practicing the basal body temperature (BBT) method,” Gotlieb explains. “Your basal body temperature is your body's temperature at complete rest or your lowest temperature. If you're using the BBT method to chart your fertility, you have to take your temperature first thing in the morning before getting out of bed, as moving around, talking, or even being awake for several minutes can affect your results.”

Presumably having Oura measure temperature at night and getting an average transmitted to your app means less human error, since if you forget to take it or jump out of bed to pee before taking your temperature, you still have accurate data. Plus, Natural Cycles says that their algorithm further reduces the chance of error. "The app has a unique and certified algorithm that adapts to each user’s cycle, detecting the fertile window more accurately and removing a lot of the human error that comes with other FABMs," says Kerry Krauss, M.D., board-certified OB-GYN and Medical Director at Natural Cycles.

It depends how you measure your temperature, but not as effective as other forms of birth control, and the reasons mostly boil down to the fact that nobody's perfect and the body isn't always predictable.

A big reason: The increase in body temperature happens after you've ovulated. "The most fertile days are the 2 to 3 days before this increase in temperature," The American College of Obstetrics and Gynecologists (ACOG) reports. A body temperature method "shows only when ovulation has already occurred, not when it is going to occur." Even though Natural Cycle's algorithm will adjust to your cycle when used over time, you may not be aware that you're fertile if your temperature hasn't yet gone up.

According to the ACOG, BBT results in one to five pregnancy out of one hundred in the first year, if practiced perfectly and accurately every time. This means you check your temperature every single morning at the same time when you wake up, compare it to previous days, and you are strict about not having sex at likely fertile times without a barrier method such as a condom. Natural Cycles cites a 98% effectiveness rate when used perfectly every time.

Many of us don't or can't practice this method perfectly. Even if you're using Oura Ring and you get your temperature reading automatically, you still have to remember to check the app to be sure it's a "green" day, which may not be the first thing on your mind in the throes of passion. It can also be really hard for some to forgo spontaneous sex even if you know it's risky. (And women in coercive sexual relationships with men may have even less control over when they have intercourse.)

These reasons mean that almost a quarter of women who use the traditional BBT method get pregnant within the first year of use, according to ACOG. There are also reasons beyond your control: “What if you get sick, or you become dehydrated?” says Mitchell-Derenski. “Your temperature can be affected by these things.” Stress, smoking, drinking alcohol, having jet lag or even using an electric blanket can cause temperature changes that could throw off your result, according to Planned Parenthood.

The Natural Cycles app is better: It has been found to be 93% effective when practiced "typically," a.k.a. imperfectly. The reason it is more accurate, says Dr. Krauss, is that the algorithm becomes more accurate as it learns from your data over time, and that it errs on the side of caution. "For example, the algorithm will exclude a temperature if it detects a significant change," she says, perhaps from a night of drinking or a fever, so it doesn't factor in to the app's fertility conclusion. "It will also always err on the side of caution and give users a Red Day," indicating fertility when the data isn't clear. Because Oura also measures heart rate, says Dr. Krauss, the finding of an abnormally high heart rate, along with a higher temperature, may indicate that there are other reasons besides ovulation causing your higher body temperature.

That said, some studies have predicted that basal body temperature is only about 22% accurate in detecting ovulation. And while that one study found that using shell temperature might be slightly more accurate, we don't know how that affects the outcome. (By contrast, an IUD or implant result in less than 1% of women getting pregnant in a year.) An independent study from Sweden and Norway, found that the data Natural Cycles provides its users is sometimes not enough to prevent pregnancy, because, again, a woman has to use the app perfectly, and her timing of intercourse must also be perfect.

Lastly, it's women with very predictable cycles who do best with cycle tracking methods, she says. If you don't, it is much harder to predict ovulation.

To maximize the effectiveness of the BBT method, take the following steps:

Using the Oura Ring along with Natural Cycles is not a failsafe, and to be fair, neither are some other methods (nine percent of women on the Pill will get pregnant in a year, for instance, according to ACOG, in part because they also don't use it perfectly).

To be clear, the Oura/Natural Cycles combo has far better outcomes than the old fashioned way of practicing the BBT method, but there are much more effective reversible forms of contraception, including an IUD or an implant. In areas where access to an abortion is restricted, using only a body temperature method for birth control, unless you want a baby, can result in dire consequences.

The best thing you can do is have a chat with your healthcare provider about the best form of contraception for you, based on how you live your life. With most forms of contraception, your lifestyle, consistency and understanding its limitations is critical to avoiding unintentional pregnancies.