Apple is very careful with the language it’s using around the new, juiced-up fertility and cycle tracking features on the Apple Watch Series 8. It can “inform your family planning” if you’re trying to conceive, the company said in the product announcement. It can predict ovulation but only retrospectively. 

The company isn’t making any claims that people could use the features to avoid becoming pregnant, which would take sign-off from the Food and Drug Administration. But people don’t just use cycle tracking tech in the ways companies say they should, says Rebecca Simmons, a researcher and fertility awareness specialist at the University of Utah. “Even if Apple says this is not to be used as birth control, which they do, people are going to utilize it as birth control,” she says. 

That’s why experts like Simmons say that Apple’s cycle tracking features are a missed opportunity for the tech giant to build out a more robust fertility tracking tool. More and more people are interested in keeping tabs on their fertility and on non-hormonal methods of birth control. But there hasn’t been investment from medical research to match that interest — leaving a gap that technology companies are trying to fill. Experts in fertility tracking and reproductive health, though, say that some of those efforts don’t have the rigor to meet the needs of the moment. 

“I think people who menstruate can benefit tremendously from having body literacy, and having a company like this say, yes, we agree that this is important and valuable, and we acknowledge people want this information — that’s really, really great,” Simmons says. “But this is a half-baked amount of literacy for people to utilize in a way that is safe.”

Scientific practices 

Apple’s cycle tracking feature predicts when a user might get their period based on information about previous periods and cycle length, according to the company website. Then, it subtracts 13 days from the estimated start of the user’s next cycle to find their fertile window, which the feature says runs for six days. Users can manually add a positive ovulation test result, which would adjust the predictions. Apple Watch Series 8 or Apple Watch Ultra users can add ovulation information calculated from the watches’ temperature sensors. Users can also get notifications if the app detects a “cycle deviation,” but it’s not available to people who have factors like hormonal birth control affecting their cycle.

Apple’s cycle tracking “Instructions for Use” say that the period prediction and ovulation estimates were tested in 260 and 226 users, respectively. The features met “pre-specified clinical endpoints,” according to the document. Apple spokesperson Zaina Khachadourian referred The Verge to those instructions and did not say if the company has any plans to publish data on the features.

Simmons says that method for predicting the days when someone might be fertile doesn’t align with best practices in fertility tracking. (Simmons helped develop the method that period tracking app Clue uses on its Food and Drug Administration-cleared birth control). 

Simmons hasn’t done research on the Apple feature, but she says that the fertile window shouldn’t be that short, for one — the length of a fertile window varies so widely that most methods would give a longer stretch. Subtracting 13 days from a cycle start date also doesn’t give enough information to find a fertile window, Simmons says. 

“That’s where the majority of apps and technologies fall — they’re fertility-adjacent, but they’re not really adhering to the full spectrum of all of these different physiological principles,” she says. “People are getting this information, but the information they’re getting is likely incomplete, at best, or wildly inaccurate at worst.” That’s risky if people are using that information to make high-stakes decisions around when to have sex to either increase or decrease chances of pregnancy. 

Apple, in particular, has such a market saturation and reputation for reliability that people might assume its products are more rigorous than they actually are, says Suzanne Bell, an assistant professor at Johns Hopkins University who studies contraception and reproductive health. It’s a potential issue around cycle and fertility tracking apps generally, she says. “There’s a lot of opportunity for misunderstanding and overinterpretation of the validity or accuracy of the information these apps are providing.”

Apple does include warnings in the Health app and instructions for use that people should not use fertile windows as a form of birth control, but users have to navigate through multiple screens to find it. 

People do use cycle tracking apps and products to avoid pregnancy, even though they’re not intended for that purpose. In one small study of fertility tracking apps, 4 percent of people said they used the apps for contraception. It’s not clear how widespread this practice is, but doctors hear about it anecdotally.

“More than a few patients have told me they’re using them in that way,” says Rachel Urrutia, a fertility awareness expert and reproductive epidemiologist at the University of North Carolina at Chapel Hill. 

Two tech companies, Natural Cycles and Clue, have developed and tested apps that are intended as birth control. Both ran studies that found the products could effectively prevent pregnancy if used correctly. The Food and Drug Administration cleared Natural Cycles as birth control in 2018 — which was a controversial decision — and cleared Clue’s birth control in 2021. 

Urrutia says that these two birth control apps aren’t perfect and that there are elements in each she’s pushed back on in the past. (She doesn’t have a formal relationship with either). But she likes that they’re transparent about their methods and that they’ve done the work to test their products and publish their results. “They’re at least trying to share their data,” she says. 

Apple, on the other hand, has only released minimal data around its fertile window and period prediction feature. 

“Apple isn’t saying that this method is to be used for birth control. So technically, they’re not in the same realm of responsibility,” Simmons says. But they should take on some of that responsibility if they’re going to make predictions based on user data and not just compile that data, she says. She doesn’t think companies should be giving users a fertile window unless they’re validating their approach and sticking closely to best practices around fertility awareness.

“I think it’s when tech companies step in and say, ‘This is what’s happening to you,’ that they merit more scrutiny — and possibly more critique,” Simmons says. 

A gap in the market

Tech companies like Apple add features to their products that people are interested in, and they’ve identified a pent-up demand for information about fertility. It’s an area that historically hasn’t been taken as seriously by the medical establishment, Urrutia says. “I finished an OB-GYN residency training without understanding how to use fertility-based methods,” she says. 

There hasn’t been major research investment into fertility awareness, even though it can be an effective tool to prevent pregnancy when used correctly. Doctors aren’t as able to help patients who are interested in monitoring their own fertility. “They haven’t been sexy to research, and they haven’t been sexy to fund because they’re really nitty gritty, and they’re a lot of work for people to do,” Simmons says. 

That lack of investment on the medical side has left a knowledge gap that’s been all too tempting for big tech companies with health and wellness ambitions to fill. These companies are founded in part on the goal of making complex and detailed tasks simple and automated for their users — and they can move faster with more funding than the medical establishment. They’re able, then, to quickly push out features that promise to track fertility easily. But they’re not disclosing the research they based the features on, they’re not publishing their data, and they’re not opening up their programs to outside scrutiny. 

Tech companies have the money — and the data — to invest in the research that could give people a better understanding of how well fertility awareness works for contraception and conception. That type of work could also help lend more legitimacy to a field that’s been under-evaluated.

“I would love to see Apple use their resources to really rigorously evaluate this sort of feature,” Bell says. Then, people could be more confident — or have more information — in making a decision on whether to use a product like a smartwatch to help them avoid pregnancy or to try and become pregnant. “It would be great for people’s reproductive self-determination and autonomy to have this feature. But it needs to be done well and evaluated rigorously,” she says.

If the tools are effective, it could be a way to help meet the needs of people who want to build a more detailed understanding of their bodies. It’s good to see big companies like Apple talking vocally about those issues. But the stakes are high, Bell says. 

“I think, on the whole, it’s potentially great that tech companies are interested in this space and meeting this need,” she says. “I just hope that they do it with the respect and rigor that is needed because this is people’s fertility and people’s lives that could be significantly impacted by reliance on these apps.”