An app. That’s what I use for contraception. Not inserted anywhere or wrapped around anything. And not for in-app purchases of creams, jellies, or barriers. I use it to chart my ovulation cycles to avoid pregnancy.

I have noticed a number of women using smartphone apps to become pregnant—as well as to avoid it. The apps offer help in both directions. Brace yourself, as you’re about to read about the sexier side of the quantified self.

Contraception’s problematic sides

In my twenties, I believed the ad campaigns about Ortho-Cyclen telling us that the birth-control pill was good for our skin and bodies because it regulates menstruation and hormones. I dutifully took it for the better part of a decade, despite regular nausea.

Fifteen years later, I am happily married with two children, and my husband and I have decided that we do not want any more kids, and I went back on the pill for a month after I finished nursing my younger child. The nausea returned with a vengeance, and I researched an alternative.

Some women take the pill for the duration of their reproductive years without issue. But not all. The pill can lead to an increased risk of heart attack and stroke, especially in older women. I flushed my 28-pill pack down the toilet.

I decided against an intrauterine device (IUD). One form relies on the slow release of hormones, which I didn’t want to add to my body; the other, which contains copper, slows sperm down, but also inflames the cervix to produce a sperm-killing reaction. Inflammation! Read any medical book or article these days and you will see this message time and again: inflammation causes disease—so, no, not for me.

Of course there are surgical options: snip him or tie me. We haven’t ruled these out but also haven’t been able to emotionally commit to them either. In the meantime, for contraception…wait for it…there’s an app for that. But not all apps are created equal.

Get on the cycle

Fertility apps work by tracking a woman’s ovulation to predict fertility; the most popular include Glow, Kindara, and iOvulate. The apps tell you the days you are most likely to get pregnant, so you can either get it on during those days, or use a barrier if contraception is your goal. Some fertility apps, such as iOvulate, use the rhythm method, while some, such as Kindara and Glow, use a method called Fertility Awareness or FA. There is a big difference in effectiveness.

FA uses a woman’s vital signs such as daily basal metabolic temperature, menstruation, cervical fluid, and cervical position to tell her exactly when she ovulates. (The last one is optional for the squeamish.) The rhythm method uses the calendar alone, and estimates that ovulation occurs 14 days after menstruation. For many women it does, but not all; it has a high rate of failure. Using FA, I’ve learned that I ovulate on day 17. For this reason, an app that uses FA is far more accurate.

I started using an app for contraception about six months ago, and picked Kindara both because the app tracks the most data points and because its charts resemble those from Toni Weschler’s Taking Charge of Your Fertility. This book was my first stop, as it was for many women, in learning about natural birth control and—wow! What a revelation! Weschler asserts that fertility tracking is empowering for both women and couples. When a man understands his role, he takes on more responsibility. Glow even lets you share charts with your partner if he downloads the app to his phone.

(Weschler, by the way, teaches you exactly what reproduction is all about, and makes the keen point that women are never taught much about their cycles other than how to clean it up and keep it discrete. I spoke with a few friends who have also read this book, and they all had the same response: how have I reached this age without knowing this about my body?)

For me, a combination of FA and an app is the best method of contraception available given my current choices, but it requires a lot of commitment. As Weschler points out, it is only for women who are in committed relationships, are willing to chart their vitals on a daily basis, and have regular cycles. And, of course, it provides no defense against STDs. Weschler says that those who are the most successful with this method are educated, upwardly mobile women who have the time and attention to detail to track data consistently, and choices available to them to make this work.

As you might expect, not all doctors are on board with this. When my husband asked his primary-care physician about getting snipped, he mentioned that we were currently using FA. The doctor’s response: “You’re playing with fire, my friend.” My midwife practice was much more accepting. They even let me email them my charts straight from the app for consultation. That’s the beauty of Kindara and some of the other apps: you can export the data to share with your doctor.

Most of these apps are free, with in-app purchase upgrades for extra features like fertility prediction, making them easy to give a try.

Your mileage may vary

I certainly do not advocate that every woman flush her birth control pills as I did. (And disposing of medicine through take-back programs may be better, in any case.) But I do advocate that women learn more about their reproductive health and empower themselves with this knowledge.

App-based fertility charting has put me in touch with my body in ways I could never have expected. It is a risk, but hormone-based birth control is too. As young women, we are given little information before someone writes us a scrip for pills. That shouldn’t be. These apps put more tools and more choices in our hands.