Experts share how tracking periods and fertility with apps like Natural Cycles stacks up against other methods.
From https://www.huffpost.com/entry/fertility-tracking-apps-birth-control_l_5d0117bee4b0dc17ef02a10a
From https://jamesjohnson10.blogspot.com/2019/06/want-to-use-birth-control-app-as.html
James Johnson 