When I was trying to conceive my second child I was monitoring and stalking every aspect of the process. I specifically bought a Fitbit to give me a behind the scenes secret knowledge of how my body works. During the time I was trying to conceive I stumbled across a post about how a woman's husband accidentally discovered his wife was pregnant by posting a question on Reddit. He posted how his wifes Resting Heart Rate had been higher than normal for a few weeks and she was constantly in the Fat Burn or Cardio zone when she was just sitting still. Reddit users suggested maybe the change was due to her being pregnant and her heart was acting that way for that reason. Well, turns out the users were right, she was in fact pregnant and her Fitbit showed so before she used a pregnancy test.