Cerviva or Bust

It didn’t start out as a quest to give cervical fluid a more palatable name. It started, as so many things do, because of love. And sex.

“ ‘Cerviva,’ ” said Will Sacks, seated in a coffee shop near his home in Boulder, Colorado. He wore a blue T-shirt that matched his eyes; behind his trim beard was a warm smile. “We wanted to start calling cervical fluid ‘cerviva.’ Cer-VEE-va. Pretty good, right?”

It was a brisk fall morning, and Will, an entrepreneur in his late thirties, was telling me about the connection between cervical fluid—also called cervical mucus—and Kindara, a company he co-founded that develops apps and products for fertility tracking. And cervical mucus, a fluid secreted by the cervix, changes in texture, color, and amount during a woman’s menstrual cycle, especially around ovulation. Until recently, most of what I knew about cervical mucus involved words like “sticky” and “egg-white.” But I’d done my homework before meeting with Will, because I realized that in order to grasp what Kindara did for its hundreds of thousands of users, I would need to understand cervical mucus and ovulation. And to talk about ovulation, I quickly learned, requires a working knowledge of the cervix.

A woman’s cervix acts as the gatekeeper to her uterus. The cervix—the “neck” of the uterus, about one inch long, positioned at the top of the vaginal canal—decides what and when things go in and come out. Tampons, sex toys, fingers, and penises can all get to the cervix, but they don’t get past it. And things like menstrual blood and perhaps a baby need to get out. The cervix’s job is to safeguard the uterus—like a bouncer poised outside a fancy, VIP-only hotel—and keep this crucial part of a woman’s reproductive system happy and healthy. Outside the cervix, sperm are lining up and competing to get in. Cervical mucus, acting as a protective barrier to the uterus, has two jobs depending on where a woman is in her cycle. Either it prevents sperm from entering the cervix or it nourishes and protects the sperm as they move through the cervix and reproductive tract to fertilize an egg. So at this particular party, if a woman is nearing ovulation, cervical mucus keeps the sperm alive, sweaty and dancing, while inside the uterus an egg makes its way down to the lobby. Once the cervix determines which lucky sperm are worthy enough to enter, the fun really begins.

I had asked Will to coffee to learn more about Kindara, and about fertility- and period-tracking apps in general. Most women I know—whether trying to conceive, actively avoiding pregnancy, or falling somewhere in between—use an app to track their menstrual cycle. And each swears by the one she uses. Kindara, in particular, intrigued me because of what it’s based on: fertility awareness-based methods of birth control, also called FAMs or FABMs. “Fertility awareness” is a general term for the set of practices used to determine the fertile and infertile phases of a woman’s menstrual cycle. A woman is fertile only a handful of days each month—around ovulation, when the egg is released. Fertility awareness-based methods are essentially about answering one question: Am I fertile today? People using FAMs identify and track fertile days and draw upon that information to avoid or achieve pregnancy. A woman does this by tracking the hormonal fluctuations that occur during her menstrual cycle, paying close attention to signs of ovulation in particular. Two primary ones are her basal body temperature and the consistency of her cervical mucus. Taken together, these physiological indicators can help her monitor her ovulation patterns and reliably identify the days when pregnancy is possible.

—

One August, more than a decade ago, Will was twenty-nine and in need of a change. Originally from Quebec, he was living in Toronto and had recently quit his job as an energy efficiency consultant. He dreamed of being an entrepreneur, using his engineering background to create companies that would have a net-positive impact on society and the environment. Companies that did things that mattered. He decided to attend his first Burning Man festival, which he was pretty sure was a thing people his age did when they were having a quasi-existential crisis. He booked a plane ticket to the desert and, upon arriving at the Reno airport, posted a message on Craigslist saying he was headed to Burning Man, had a rental car, did anyone need a ride? Kati Bicknell, a young woman from Brooklyn, answered. Petite and fair-skinned, with wavy brown hair and dark blue eyes, Kati worked for TED Conferences. They talked the entire drive into the desert.

After Burning Man, they started dating. “We got along like a house on fire,” Kati told me. It was a long-distance relationship from the start, maintained with overnight buses between New York and Toronto. One weekend night in November, a few months later, the couple had a conversation about birth control. For Kati, fertility was a familiar topic. Her mother was one of the two million women who had been fitted with the Dalkon Shield, the defective IUD. Kati’s mother struggled to conceive her. And Kati had had an IUD earlier that year, but it was so painful she’d had it removed. That, along with a bad experience on the Pill—she’d reluctantly taken it in her late teens and early twenties to “correct” her irregular periods—led her to swear off hormonal birth control.

It’s commonly assumed that women, especially those in long-term relationships, will bear the responsibility of preventing pregnancy by using a contraceptive method like the Pill or an IUD. The ubiquity of hormonal birth control makes this even more commonplace. As an adult, Kati developed strong feelings about how the division of labor in birth control plays out in women’s lives. She also found it deeply unfair that women are saddled with dealing with hormonal birth control’s side effects. She was done with the Pill and IUDs, but after settling into their relationship, neither she nor Will wanted to continue using condoms. Kati, a trained FAM instructor, had been charting her fertility for the past year. She mentioned this to Will one day. When Kati began telling him about fertility tracking, Will told me, he laughed at her. “There’s no way that can be real,” he recalls saying. “I’ve heard of the ‘rhythm method.’ It doesn’t work.” That was the end of the conversation. The next day, Kati handed Will her worn copy of Taking Charge of Your Fertility, the formative book about reproductive health and natural birth control by Toni Weschler, and told him to read it. Will was more than skeptical. But as he paged through the book and learned more about FAMs, his skepticism splintered into questions. “I said to Kati, ‘Wait a minute. You’re telling me there’s a method of birth control that’s nearly as effective as the Pill, has no side effects, is hormone-free, and costs nothing—and that nobody knows about it?” He found it hard to believe, yet was deeply intrigued. “I was like, ‘How is this possible? There’s no way this is possible.’ ”

Will is polite, measured, always paying attention. He avoids caffeine, which maybe has something to do with his calm demeanor. He locks eyes when he’s speaking. He says things like “There’s, like, four forces that are coming to me as you’re talking” and “I just really think it’s the patriarchy.” He had crumbs in his beard for most of our conversation. “I thought I was a progressive man,” he mused, sipping from a mug of herbal tea. “I’d have conversations about hormonal birth control. I understood the different methods. And then I read this book and I was like, ‘Oh my God. I don’t know anything about how women’s bodies actually work.’ ”

Will recounted all this to me matter-of-factly, with an air of confidence that indicated his ignorance hadn’t lasted for long. It sounded like the ripe beginnings of a good origin story: An enlightened woman meets a self-assured man who is woefully misinformed about the female body. Then, a plot twist. It turned out that Will reading a thick book about fertility would change both his and Kati’s lives for the better.

—

A national bestseller, Taking Charge of Your Fertility is the FAM bible. The book was originally published in 1995 and has become one of the most universally lauded health books on the market. In it, Weschler describes FAMs and explains the concept of charting menstrual cycles as a way for women to practice effective natural contraception, maximize their odds of getting pregnant, and command their gynecological and sexual health. “Your menstrual cycle is not something that should be shrouded in mystery,” Weschler writes in the book’s twentieth-anniversary edition. “The best thing to come out of my years using the fertility awareness method was the privilege I felt in being so knowledgeable about a fundamental part of being a woman.”

Will was intrigued by Taking Charge of Your Fertility. He learned that there are a few different FAMs that help a woman track her ovulation and fertility patterns, and that FAMs are used by women all over the world who are drawn to them simply because they don’t involve the kind of chemicals associated with hormonal methods of birth control like the Pill—and because they minimize the frequency with which they’d choose to use condoms, a diaphragm, or other barrier methods of birth control. He learned that many couples use FAMs to avoid getting pregnant, but that they can also be an aid when trying to conceive. And he learned that charting fertility is a good way for a woman to be on top of her gynecological health in general; it’s easier to tell what’s normal and what isn’t when you’re tracking what’s going on down there.

Will’s initial quick leap to misassociate FAMs with the rhythm method is, unfortunately, a common one—and it’s a major reason there remains some stigma and confusion surrounding it. The rhythm method involves simply counting the days starting when a woman’s period ends and then abstaining from sex around day fourteen, the assumed midpoint of her cycle and when she is supposedly most fertile. Will had been mostly right in his comment to Kati, as the rhythm method is one of the least effective methods of contraception. What he didn’t know was why: because it falsely assumes that all women have twenty-eight-day cycles and that cycles are reliably consistent over time. The length of a woman’s menstrual cycle is the number of days between periods, counting the first day of your period until the day before your next period starts. The notion that a normal menstrual cycle is twenty-eight days is a routinely accepted myth, perpetuated by a slew of medical sources, from diagrams in sex ed classes to birth control pill packaging. In fact, cycle lengths vary among women, ranging anywhere between twenty-one and thirty-five days, and often vary for an individual woman as well. A woman might ovulate on the twelfth or the twentieth day of her cycle. The idea that ovulation happens on day fourteen, then, is arbitrary—and getting it wrong can have serious implications for contraception science.

Having learned the basics about women’s fertility, Will found the bit about cervical mucus particularly fascinating. Composed of nutrient-rich electrolytes, proteins, and water, cervical mucus shares a purpose with semen: to help sperm reach and fertilize an egg. Ovulation triggers the cervix to produce various kinds of secretions; the wetness a woman might notice on the crotch of her underwear at different times of the month differs depending on where she is in her menstrual cycle and usually follows a predictable pattern. She can check her cervical mucus every day, looking for changes in quality and quantity—dry, sticky, creamy, egg-white—and have a pretty good sense of where she is in her cycle and if ovulation has occurred.[*1] She can also take her temperature in the morning every day before getting out of bed. This is basal body temperature, or BBT, your body’s temperature when it’s completely at rest.[*2] BBT measures ovulation; progesterone, the hormone that prepares the uterus for a fertilized egg, causes BBT to rise, signaling that ovulation has occurred.

Somewhere around page 164 of the book, Will told me, he had an epiphany. He’d read that conception is only possible from about five days before ovulation through to the day of ovulation. Sperm can live for up to five days in a woman’s body, so if a woman has sex up to five days before the egg is released, she can get pregnant. After ovulation, the egg can live for up to twenty-four hours, which means that once it’s released from an ovary, the egg can be fertilized as it travels through the fallopian tube toward the uterus. Fertilization happens when a sperm cell successfully meets an egg in the fallopian tube. Known as the fertile window in a woman’s cycle, these six or so days are the only time each month when having sex can lead to pregnancy.[*3] So, the length of a woman’s fertile window takes into account the combined life span of an egg (about twenty-four hours) and sperm (roughly five days). The trick is figuring out exactly when that window is—and, like menstrual cycles, fertile windows vary from person to person. All this is why determining the few days around ovulation is the crucial component of fertility tracking.

So then Will got it. By observing and tracking signs of ovulation like cervical mucus and basal body temperature, as well as using a calendar to chart her menstrual cycle, a woman could estimate her fertile days. And that, Will realized excitedly, was information he and Kati could use. They could choose not to have sex on the days that made up Kati’s fertile window, or if they did, they’d use a condom or another barrier method of birth control. That was it; he was sold. FAMs would be their natural birth control. It would require careful, daily monitoring, but the nerd in him was more than up for that. Will finished the book—and told Kati he was in.

Using FAMs and tracking fertility patterns helped Will better understand Kati and helped Kati better understand herself. And gone were the days of “I’m wearing a condom, so I’m responsible” or “She’s on the Pill, so she’s responsible”; by practicing FAM, Will and Kati shared the responsibility of protecting against pregnancy. But amid the newfound intimacy in their relationship, Will couldn’t stop thinking how mistaken he’d been about how women’s bodies work. He knew this kind of ignorance was pervasive. And he was fairly certain there were many, many more people out there who, once they realized they didn’t know what they didn’t know, would feel forever changed by discovering a form of natural birth control that, if practiced correctly—and this is key, practiced correctly—was very effective at preventing pregnancy.[*4] And those people, Will predicted, would likely need some help figuring out the best tools with which to reliably use FAMs. This will change the world, he thought. Kati agreed.

Their vision was to use technology to empower women through body literacy, while simultaneously helping to improve how men and women relate to each other. Will, an engineer, and Kati, a product designer, set out to find the best tech with which to track Kati’s cycle—and quickly realized it didn’t exist. So they decided to create it themselves. That winter, they ditched their jobs and moved to Panama to save money. In a rented house near the ocean, they secured freelance gigs to cover their living expenses but spent most of their time devouring studies and the latest scientific research. They returned north a few months later and, with pitch in hand, started filing patents for an app and a digital BBT thermometer that would make it easier for couples to chart ovulation and fertility patterns.

I tried to imagine this bearded, herbal-tea-drinking man in a boardroom, pitching a bunch of all-male venture capitalists while clicking through PowerPoint slides about periods, fertile windows, and carefully timed sex. I could picture a few men loosening their power ties; someone coughing, clearly embarrassed; and maybe some of them wondering why they’d never heard about any of this before. “We got pooh-poohed by a lot of people,” Will said, gripping his mug. I asked why; he gave me an isn’t-it-obvious look. “Because I was talking about cervical fluid and starting a business. People were like, ‘What is that? I don’t want to hear about that. It makes me uncomfortable and, also, what the hell are you talking about?’ ” But he wasn’t deterred.

The couple moved to Boulder, a town that had recently been named as having the most tech start-ups per capita of any city in the United States, and set to work translating their ideas into a company. Two years later, in the summer of 2012, they launched the fertility-tracking app that they had designed themselves. In between, they got married at Burning Man, on the first anniversary of the day they met. Will and Kati started with limited cash and skills, but the venture capitalists stopped scoffing—Kindara raised around $10 million in funding—and the couple built Kindara into one of the first venture-capital-funded digital women’s health companies in the world.

The app’s main features—an ovulation calculator, BBT chart, and period calendar—can be used not only to help a woman get pregnant or avoid pregnancy but also to help chart her menstrual cycle simply for her overall health. Users can input days they have sex and days they menstruate, get ovulation predictions, and record changes in cervical mucus and BBT. For Erin, twenty-eight, a loyal Kindara user, the best part about the app is the self-knowledge factor. “Fertility tracking has helped me to understand so much more about my body, my mood, and overall health,” she told me. “Really getting to know their own unmedicated cycle should be something all women are encouraged to do.”

I’ve met my fair share of entrepreneurs and start-up founders who talk about being a force for good, but Will and Kati struck me as the real thing. They have moved on to other ventures since starting Kindara—the company has been acquired by another Boulder-based women’s health company—but remain visibly stoked about normalizing the conversation around FAMs and helping people feel empowered when it comes to sexual well-being and fertility. “We get all kinds of letters and emails from people saying, ‘Oh my God, I understand my body for the first time now. Thank you,’ ” Will told me. “That’s been the best part of the whole ride.” From the beginning, Will’s relationship with Kati inspired how he thought about Kindara. “I think we’re fucked up about sex and intimacy from an early age,” he said. “I was like, ‘I want every couple to have the experience we were having—feeling that connection, learning about each other’s bodies, having that level of intimacy.’ ” The steep learning curve was worth it. Will summed it up to me like this: “I don’t think there are a hundred people in America who know more about fertility awareness than Kati and me.”

I was struck by the realization that the man sitting across from me knew a great deal more about the female reproductive system than I did. Which absolutely delighted me. Maybe I shouldn’t have been surprised by Will’s openness. Still, it was so refreshing to talk about sex, birth control, and the role technology plays in the future of fertility education—and with a man not too much older than me that I hardly knew. To talk about these things with a man at all! I had reached out to Will to learn the ins and outs of starting a women’s-health-focused technology company. But as we talked in the coffee shop that day, I realized I was just as interested in the why behind Kindara, the ways in which he and his partner—in business and in life—navigated the potentially awkward, messier parts of their relationship, the ones having to do with sex and contraception and romantic things like cervical mucus. I listened to him describe his journey from stunned ignorance to cool-as-a-cucumber “wokeness” with some envy. When was the last time I’d had a frank, science-based discussion about vaginas and penises with a man? Had I ever?

His comments about the burden of birth control nagged at me, too. Will and Kati’s head-on conversations around contraception struck me as progressive, and that didn’t sit well with me. I would like to believe that safe sex—protecting against pregnancy and STIs—was a shared responsibility between two people sleeping together. But in my experience it seldom played out this way. In fact, on the potential pregnancy front, I could not recall a man ever initiating a conversation about protection before we had sex. In most of my relationships and sexual encounters throughout my twenties, I’d offer up the fact that I was on the Pill early on in conversation and that was that. What bothered me—and, based on the experiences of many other women I’ve discussed this with, them too—was the assuming, how men frequently wait until the woman asks him to put on a condom before doing so and doesn’t ask before sex if she’s on some form of birth control or not.

My frustration in this regard was relatively new; for years, I thought nothing of taking primary responsibility for pregnancy prevention. But my tune had changed. It wasn’t just that I found the double standard irritating. An unplanned pregnancy is a consequence for both parties, so leaving women to shoulder the burden of preventing pregnancy struck me as just plain dumb and irresponsible. Now this thought is never far from my mind when I’m deciding whether or not to have sex. Do men really just not think about this? Or if they do, is it merely a passing thought, dismissed with the assumption that the woman’s got the protection handled? The most troubling bit underlying that assumption, I realized, was that it actually wouldn’t be on both my partner and me. Because it’s my body, my decision—at least ultimately. Right?

I haven’t worked out the answer to this question yet. Yes, it’s my body, my business—not his. But men should be asking their sexual partners about birth control; both men and women should initiate the conversation about protection. Just like both men and women—all people—should know the basics about both female and male fertility. The burden of birth control, I had come to realize, extended to the management of women’s fertility. Men do not experience the same pressures to manage their fertility, and in the same way that pregnancy prevention is often left to the woman, so too are the expenses and decisions related to preserving fertility, particularly for young women freezing their eggs.

“Fitbit for Your Period”: The Rise of Fertility Trackers

While Will and Kati were hustling to get Kindara off the ground, the fertility-tracking space was heating up. In 2013, a year after Kindara’s app launch, Max Levchin, co-founder of PayPal, helped launch a period-tracking app called Glow, which raised $23 million in venture funding in its first year. The race to hack women’s menstrual cycles was on.

If learning about hormones and menstruation led me to Kindara, then Kindara led me to the world of femtech. Depending on whom you ask or what you read, femtech is a concept, a movement, or some Silicon Valley lingo. Actually, it’s kind of all three. Ida Tin, the Danish entrepreneur and co-founder of Clue, a popular period-tracking app, is widely credited with coining the term, which refers to products, software, and services that use technology to improve women’s health. Femtech, powered mostly by female entrepreneurs, is geared toward improving healthcare for women across a number of conditions specific to people with ovaries, including maternal health, pelvic and sexual health, menstrual health, fertility, and menopause.

“The Fitbit for your period” is a good sales pitch, and Will used it when talking with investors about Kindara. On the heels of Kindara came a boom of other female-focused apps and technologies to support women of reproductive and post-reproductive age. The market for digital women’s health and femtech products is big: women from puberty to menopause. Personalized testing products and do-it-yourself healthcare have never been so popular, and a slew of pioneering developments—from period-tracking apps to at-home hormone tests to wearable fertility-monitoring devices—have burst onto the scene. Meanwhile, mobile technology has rushed in to fill the reproductive health knowledge void in the same way it’s rushed into virtually every other part of our lives. The trendy companies behind these new digital applications focus on a range of issues, from charting ovulation via AI-based apps to supporting women experiencing low libido to marketing period care goods to financing fertility procedures like egg freezing. Part of broad shifts in digital medicine, they also illustrate femtech’s potential to revolutionize women’s health. There are Bluetooth-connected breast pumps, pelvic floor exercisers, digital bracelets that track ovulation, subscription-based services that deliver organic tampons to a woman’s front door, and a lot more. Wearable and digital fertility monitors, period-tracking apps, and at-home fertility hormone tests are the major ones I’ll go into here.

Can Silicon Valley get you pregnant? Many femtech companies are screaming yes. Do women want to manage their reproductive health with their smartphones? Oh, absolutely. The global femtech market is projected to be worth more than $100 billion by 2030, and investors—primarily the world’s mostly male venture capitalists, who customarily all but ignore women’s health—are now paying attention.

Smart wearables have been booming for some time, since biosensors in mobile devices make it easy to record, store, and analyze data about the user’s body and behaviors. The most popular ones in the femtech world are external and internal electronic devices and digital fertility monitors—a catch-all term for any device that helps a woman track her fertility, especially regarding ovulation and potentially getting pregnant. Fertility monitors do this in a few different ways—such as measuring hormone levels and BBT in order to predict fertile windows—and work in much the same way as FAMs. Some analyze urine samples (the user pees on a wand, then sticks the wand into the device); others measure BBT or cervical fluid via a vaginal sensor while a woman sleeps (she inserts a discreet, tampon-esque device at night and, after removing it in the morning, holds it near the back of her phone while her data downloads to the device’s corresponding app).

One of the most popular digital wearables is the Ava Fertility Tracker, a cycle-monitoring sensor worn like a bracelet overnight. It’s the first—and, as of this writing, the only—FDA-cleared stand-alone fertility-tracking wearable. The device detects the user’s menstrual cycle phase—and fertile window, with 90 percent accuracy, according to a recent study—by tracking physiological signs such as skin temperature, heart rate, and respiratory rate, which act as markers for fluctuating hormone levels. Fans of Ava say it’s easy to use and is more convenient than ovulation test kits. Some users credit their pregnancies to their Ava bracelet—$279 a pop, as of this writing—and for those who pay more for premium packages, the company offers a full refund if the user isn’t pregnant within six months or a year.

Other popular fertility-monitoring products on the market include digital ovulation kits, insertable cervical mucus monitors, and BBT thermometers. Some people use fertility monitors to help them avoid pregnancy without taking birth control, but more commonly women use these products when they’re trying to become pregnant; tracking ovulation helps couples conceive, but manually charting cycle symptoms can be arduous, and these tools streamline the process and make fertility monitoring much easier. They’re not omnipotent, though—none of the devices are approved to prevent pregnancy—and aren’t a replacement for seeing a doctor, which is sometimes necessary; even the most high-tech digital fertility monitor can’t diagnose problems that could explain why a couple is struggling to conceive, such as low sperm count or endometriosis.

So many women wake up to their fertility only after struggling to become pregnant. Others go through early adulthood at least aware of their monthly bleeding and PMS symptoms, even if that awareness never quite shifts to a true understanding of what’s going on. As they tell a woman about the whens and hows of her cycle—in addition to cluing her in to her overall health—digital fertility wearables and devices are powerful tools that help bridge this gap. So are period-tracking apps, which are among the most frequently downloaded kind of health app in the App Store. Also called ovulation trackers, cycle trackers, or just fertility apps, they’re used by people wanting to prevent pregnancy, people trying to have a baby, and people looking for an easier way to monitor menstrual-cycle-related health issues. A user is invited to input intimate details every day—the length and heaviness of her menstrual flow, types of period-related pain such as cramps and headaches, whether she had protected or unprotected sex, fluctuations in libido—which the app uses, along with dozens of other optional data points the user chooses to input, to make its predictions. As with digital fertility monitors, fertility apps rely on the same physical fundamentals that FAMs do, those externally observable physiological signs that indicate where a woman is in her menstrual cycle (the two major ones being BBT and the color and consistency of cervical mucus). Each app has its own algorithm, but all draw upon user-inputted data to generate predictions around ovulation, fertile windows, and estimated period start dates.

I use Clue, an early pioneer in the femtech world whose app has over eleven million users in 190 different countries.[*5] Clue’s co-founder, Ida Tin, suffered side effects from hormonal birth control for years; like so many femtech founders, she set out to build something after personal experience left her frustrated and declaring, There’s gotta be a better way. I use “Clue Period Tracking” mode, but it also has a “Clue Pregnancy” mode, which I could transition to in the future. The app makes it easy to review my cycle history and symptoms, and gives me predictions based on my tracking. In other words, it does a lot more than simply tell me when I should expect to bleed each month.[*6] Clue helps me calculate the average length of my cycle and uses that information to help me predict my next “period” (not a real period, remember, but rather withdrawal bleeding, since I’m on the Pill). It offers a multitude of options for what I can track. I can toggle on all sorts of reminders related to my period starting, fertile window coming up, birth control pills, time to check BBT, and more. I don’t need most of these toggled on, since I don’t closely observe my fertility signs, but I like that Clue is designed to support FAMs. I like that it was easy to set up and is intuitive to use. I like that it teaches me about my body and personal biology. I like that it’s transparent about citing the research and data it draws from. I like its clean, modern interface and inclusive tone. And I really like that it’s not pink.

Because I tell Clue every day that I’ve taken my birth control pill, it doesn’t show me predicted fertile days (the feature that shows a user her high- versus low-risk days in terms of possible pregnancy isn’t displayed if she’s told the app she uses hormonal birth control). But the app takes into account how my specific birth control method may be affecting my cycle and fertility. Nearly every day, I open the app and chronicle period-related symptoms I may be experiencing—cramps, fatigue, stress—as well as make notes, if I want to, about sleep, exercise, eating, and a whole host of other factors, all of which impact my cycle. I also tell Clue when I’ve had sex. This admittedly felt a bit weird at first, my iPhone usually knowing more about my sex life than any human in my life does. But it’s helpful: On days I am “intimate” I make a quick note as to whether it was protected or unprotected sex. Since I’m on the Pill and take it exactly as I’m supposed to, this feature doesn’t matter so much—except for the very infrequent mishap, like when I went on a last-minute reporting trip out of town and left my pack of birth control pills at home. I logged “missed pill” in the Clue app, at which point it shouted at me (nicely) to use a condom if I had sex that weekend.

“The sex ed you never got,” Clue’s website touts. Clue’s customer service team receives thousands of health-related inquiries from users about sex, menstruation, fertility, and more. The most common questions: Why is my period late? Why is my cycle irregular? Do I need to seek medical care? Because being on the Pill stops me from ovulating, I’m honestly not always sure whether changes in my body from month to month are a result of the synthetic hormones or if they have nothing to do with my non-cycle at all. But over the years I’ve switched up the brand and type of birth control pills I take, and every time I do, my body takes a while to adjust. Keeping track of symptoms helps me identify patterns and better understand hormonally influenced changes to my body—a small but very real comfort. When I open the app and input a piece of information—that I took my pill that morning, say, or that I broke out with a bout of acne—a little wheel at the top spins and it tells me “Clue is getting smarter…,” and that makes me feel a bit more tuned in to my body and all that’s going on in places I cannot see.[*7]

Fertility tracker apps aren’t perfect. When researchers at the University of Washington collected data from two thousand reviews of popular fertility-tracking apps and surveyed nearly seven hundred people about them, they found that users were dissatisfied with the apps’ lack of accuracy and their assumptions about their sexual identity. Most are geared toward heterosexual and cisgender women, many responded, and they disliked the emphasis on pink, flowery interfaces at the expense of customization.

And it’s true. A major drawback of period-tracking apps is their propensity for inaccuracy. Many of the apps assume that a user’s most fertile days are her ovulation date and the five preceding days. But, again, this so-called regular cycle—meaning she always gets her period every twenty-eight days—is not the norm for most women. Also, ovulation tends to shift from month to month. And so the fertile window the app tells her could very well be wrong. The more carefully and consistently the user tracks her cycle, the more accurate the app will be. The app’s estimations improve over time because the longer a user tracks and the more information about her cycle she supplies, the more data the app’s algorithm has to work with. Most of the apps let you program them to send you input reminders, as I’ve done with Clue. Still, it can be easy to forget to be diligent about updating and engaging with the app every day. If a woman is using the app as a reliable digital record of her menstrual cycle, the stakes are low if she misses a day here or there, especially if she uses hormonal birth control. But if she’s relying on the app to avoid getting pregnant and doesn’t use any form of birth control, being just one day off can result in an unintended pregnancy.

Another drawback is privacy concerns. Millions of women around the world use apps to track their cycles, and that treasure trove of data is often passed on to third-party companies such as Google and Facebook. Apps in general offer very little in the way of data privacy rights when it comes to the information that’s shared with them, and fertility apps are no exception. Some of the apps allow users to remove their identity from the data it has stored on them, but many don’t, meaning that a user’s information isn’t anonymous. A 2022 Consumer Reports study that evaluated privacy practices and data security for several fertility apps concluded that while some make it easy for users to understand what information is collected, all the apps “share some user data with external partners for purposes such as targeted advertising. And then those partners may share or resell a user’s personal information to third parties, who of course make no promises to the user about how they handle it.”

No woman who tells an app whether she had unprotected sex or an abortion wants such deeply private information shared in a way that could identify her. This became a major issue in the summer of 2022, when data privacy issues and fertility-tracking apps took on a new, scarier meaning after Roe v. Wade’s reversal. This sparked action in some states with regard to safeguards for consumer health data collected by companies, but new federal regulatory frameworks are needed. While the United States has strict privacy laws that govern how entities such as hospitals and health insurers share information about patients, these laws don’t apply to mobile health apps, which fall under consumer privacy laws—and offer much lower standards of protection. In other words, the personal health data people enter into consumer apps isn’t protected by federal safeguards for patient privacy—including, notably, HIPAA, the federal health information privacy law.

There is a plus side, though, to anonymously sharing information of this nature, and that’s the data it provides for scientific and medical research about menstrual and reproductive health. Modern medicine was developed with male physiology as the default, and women have historically been underrepresented in medical research, clinical trials, and biology textbooks; it wasn’t until 1993 that including women in federally funded clinical research was required by law. A 2022 McKinsey report found that just 1 percent of biopharmaceutical and medical technology investment goes toward female-specific conditions beyond oncology. One percent. Considering that people with ovaries constitute nearly half of the world’s population, it’s both nonsensical and infuriating that female health remains so overlooked and underfunded.

Several fertility apps say that medical researchers use anonymized information from their apps to study female-focused health concerns. Sharing sensitive health data after telling users their information would be kept private isn’t okay.[*8] But the benefits of personal data being put to good use shouldn’t be ignored, either. The New York Times pretty much nailed it in an article about the troubling data-sharing practices of Flo, a popular period tracker: “And here lies the crux of the problem with women’s consumer health technology, or ‘femtech’ as it is known in investor speak: The sheer volume of data collected in apps like Flo is ripe for privacy violations, but that same data may also open the door to unraveling some of the biggest, understudied riddles of female health.”

Private Little Revolutions: The Truth About Hormone Testing

At her home in New York, twenty-six-year-old Margaret Crane sat at her desk, assembling a plastic paper-clip holder, a test tube, a dropper, and a small angled mirror. It was 1967, and Crane, a freelance graphic designer, had recently been hired by the pharmaceutical company Organon. While touring the company’s lab in West Orange, New Jersey, she noticed multiple lines of test tubes suspended over a mirrored surface. She was told they were pregnancy tests, and that when combined with a pregnant woman’s urine, the test tube would display a red ring at its base. “I thought how simple that was,” Crane recalled of seeing the tests for the first time. “A woman should be able to do that herself.”