The FDA approved marketing of the direct-to-consumer smartphone app Natural Cycles as a method of contraception to prevent pregnancy Aug. 10.
The app, developed by the Swedish company Natural Cycles Nordic AB, calculates the days of the month a woman is most likely ovulating, based on daily basal body temperature readings and menstrual cycle information. The app, which the FDA referred to as a "medical app," will display the phrase "use protection" on days the user is most likely to be fertile.
The FDA reviewed Natural Cycles under its de novo premarket review pathway, which is targeted toward "novel" low- to moderate-risk medical devices, the FDA noted in its statement.
To evaluate Natural Cycles, the FDA reviewed several clinical studies involving 15,570 women who used the app for contraception during an average of eight months. The app's failure rate for "perfect use" was 1.8 percent, compared to its failure rate for "typical use," which was 6.5 percent.
Typical use accounts for ways women often don't use the app correctly, such as having unprotected intercourse when the app displays the "use protection" notice.
Natural Cycles has received some pushback in Europe, where the European Union certified the app in mid-2017. In January, a Swedish hospital reported Natural Cycles to Swedish regulator Medical Product Agency after documenting 37 women who visited the hospital for an abortion after using the app.
At the time, Natural Cycles told The Verge: "No contraception is 100 percent effective, and unwanted pregnancies is an unfortunate risk with any contraception. … At first sight, the numbers mentioned in the media are not surprising given the popularity of the app and in line with our efficacy rates. As our user base increases, so will the amount of unintended pregnancies coming from Natural Cycles app users, which is an inevitable reality."
In an FDA statement announcing the app's approval, Terri Cornelison, MD, PhD, assistant director for the health of women in the FDA's Center for Devices and Radiological Health, emphasized no form of birth control is 100 percent accurate.
"Consumers are increasingly using digital health technologies to inform their everyday health decisions, and this new app can provide an effective method of contraception if it's used carefully and correctly," Dr. Cornelison said. "But women should know that no form of contraception works perfectly, so an unplanned pregnancy could still result from correct usage of this device."