Companies are hiring outside firms to track data about employees' medical claims and prescription drug use in order to monitor their health and pregnancies, according to the Wall Street Journal.

The ostensible goal of these firms is to reduce companies' healthcare costs by providing employees with healthcare information and helping them make informed decisions. For example, Castlight Healthcare, which serves companies such as Walmart, can identify when employees may be considering costly spinal surgery and send them information about cheaper fixes or ways to delay the procedure but still help their condition, such as doing physical therapy.

But Castlight also has a program that attempts to predict when employees are pregnant or trying to conceive by monitoring their search queries and scanning their insurance claims to find workers who have stopped filling their birth-control prescriptions