The Food and Drug Administration (FDA) has approved the marketing of the first app to prevent pregnancy. The app, called Natural Cycles, tracks a user’s body temperature and menstrual cycle to determine which days the user is likely to be fertile.
To use it, women take their body temperature using a basal thermometer immediately when waking up in the morning and enter it into the app. Natural Cycles uses this information to create a log to flag fertile days.
"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," Terri Cornelison, assistant director for the health of women at the FDA's Center for Devices and Radiological Health, said in a statement.
"Perfect use" failure rate of 1.8 percent
However, the agency added, “women should know that no form of contraception works perfectly, so an unplanned pregnancy could still result from correct usage of this device.”
The FDA said in a press release that during clinical studies of 15,570 women who used the app for an average of eight months, the app had a “perfect use” failure rate of 1.8 percent. That means 1.8 in 100 women who use the app for one year will become pregnant.
The company said the app had a "typical use" failure rate of 6.5 percent, which accounted for women sometimes not using the app correctly. On its website, Natural Cycles says that typical use contraceptive failure could be due to reasons such as the app mistakenly saying a fertile day was a non-fertile day or a user having unprotected sex on a fertile day.
Reports of unplanned pregnancies
The app was approved last year by the European Medicines Agency, the European equivalent of the FDA. Its approval by the U.S. FDA comes with some controversy.
Last year, a hospital in Sweden reported the app to the country’s regulatory agency after finding that 37 women who became pregnant and obtained abortions from September to December had been using the Natural Cycles app as their main form of contraception.
Natural Cycles responded that these unplanned pregnancies should be seen as an example of the small failure rate expected with typical use. The company stressed that no form of birth control is considered to be 100 percent effective at preventing pregnancy.
More than 600,000 people subscribe to the app, which costs $10 per month or $80 per year. A yearly subscription comes with a high-sensitivity basal thermometer.