Amazon CEO Andy Jassy speaks during the GeekWire Summit in Seattle on Oct. 5, 2021.David Ryder | Bloomberg | Getty ImagesAmazon has discontinued a secretive effort to develop an at-home fertility tracker, according to internal documents and people familiar with the matter.The company had been working to launch a fertility monitoring device and companion smartphone app for the past four years as part of a project codenamed "Encore," said the people, who asked not to be named because they weren't ...