Before using birth control apps, patients should consider their privacy

Score one for the quantified self-surveillance movement. Last week, the US Food and Drug Agency approved the first-ever, over-the-counter digital contraceptive—a polished and almost preternaturally upbeat mobile app called Natural Cycles. Basal body temperature readings and monthly menstruation data feed into an algorithm that tells users whether or not they should be having unprotected sex. Like most forms of birth control, it’s not foolproof; the app has been dogged by reports of unwanted pregnancies that prompted two ongoing investigations by European authorities into its Swedish maker’s marketing claims.