The Natural Cycles App, the first non-invasive, non-pharmaceutical digital birth control, sure sounds good. Available for Android and iPhones, the app is 93 percent effective at preventing unwanted pregnancies and can be used for pregnancy planning, to the tune of $99.99 per annual subscription.  There are no known side effects.

The Centers for Disease Control rates the effectiveness of IUDs at more than 99 percent, the pill at 91 percent.

Founded in Sweden in 2014, Natural Cycles had more than 800,000 subscribers in 160 countries as of June 2018, with 75 percent using it for contraception and 25 percent to plan pregnancy. Approved in Europe in 2017 and by the FDA in August 2018, Natural Cycles is intended only for fertility monitoring in other locales.

How does it work? Basically, the app analyzes menstrual cycle dates along with basal (lowest resting) body temperature, which can increase slightly during ovulation, to predict fertile days.

Sounds An Awful Lot Like Natural Family Planning…

But is Natural Cycles really just souped-up, natural family planning 2.0?

Used by women for at least hundreds of years, fertility awareness methods include tracking basal temperature, cervical mucus changes, and menstrual dates alone or in combination. The Centers for Disease Control rates “calendar rhythm” at 76 percent effectiveness – the second-least effective contraceptive choice after spermicide alone.

So, what’s the app’s secret sauce?

Natural Cycles was developed by Swedish particle physicist Elina Berglund for personal use when she wanted to help her body return to its natural cycles after using hormonal contraception, with an eye toward future pregnancy. Drawing on statistical methods used in physics, Berglund developed an algorithm (a mathematical method for solving a problem) for predicting fertility based on very precise measurements of basal body temperature to two decimal points. A household thermometer, on the other hand, only goes to one decimal point. (The app comes with its own thermometer.)

The algorithm takes into account an expanded array of factors including temperature fluctuations, variations in menstrual cycle length and ovulation date as well as sperm survival and optional self-administered luteinizing hormone (LH) test data. LH peaks about 48 hours prior to ovulation, and incorporating LH data into the algorithm, the company says, can result in a more accurate prediction of ovulation and thus fewer “red” (versus green) days when unprotected sex is not advised.

And the app does all calculations, eliminating human error.

Natural Cycles App Under Scrutiny

Like many things shiny and new, is Natural Cycles too good to be true?

A quick Google search yields articles casting doubt on the app’s user-friendliness and reliability from The Guardian, Self, Popular Science, Wired, Vox, Fortune,  Business Insider and NPR, and other outlets. On Natural Cycle’s Facebook page there are disparaging comments from woman after woman, such as “I believe in Catholic School they just call this family planning …” and “It sounds like you want to be a parent if you use that app.”

In 2018, a Swedish hospital filed a complaint with a government agency due to the number of app-users seeking abortions for unwanted pregnancies. The government found that the numbers fell within the claimed effectiveness range, but critics contend that unwanted pregnancies are underreported.

Also in 2018, the company’s “misleading” Facebook ads were banned by the British Advertising Standards Association.

The controversial FDA approval, based on an eight-month clinical study of 15,570 women, reported a 6.5 percent failure rate with “typical use,” which accounts for human error, and a 1.8 percent failure rate with “perfect use,” which attributes failure to the app itself. However, other researchers have found a nearly 10 percent failure rate, based on a review of published studies.

Natural Cycles App Requires a Neat and Orderly Life

Users need a lifestyle conducive to taking one’s temperature upon arising at roughly the same time at least five mornings a week, and lots of things can interfere with the accuracy of readings:

  • Irregular sleep
  • Hangovers
  • Insomnia
  • Feeling sick
  • Having an infection
  • Extensive smoking
  • Recreational drug use
  • Extreme stress
  • Changing time zones
  • Napping

According to Berglund’s physicist husband and company co-founder Raoul Scherwitzl, the typical user is over 30, in a stable relationship, and intends to get pregnant within a few years. The app is not recommended for menopausal women and those with polycystic ovary syndrome, thyroid conditions and other conditions associated with pregnancy risk.

Users need to be willing to abstain from sex on consecutive days each month, and women with irregular cycles will have a higher number of these “red” days. It can take up to several cycles for the app to get to know a woman’s system and accurately predict fertility, which could mean an abundance of “red” days initially.

Women, Know Thyself

Photo of two body positive women sitting in bed.

If you’re a patient, routine-oriented woman with a stable relationship and lifestyle, and you’re willing to use other birth control methods or abstain from sex on “red” days, Natural Cycles could be a safe, side-effect-free answer to your birth control prayers.

On the other hand, buyer beware if that’s not you.