I’m still in the TWW. I’ve read that your HR can indicate your fertile window and if you conceive. I just happened to look at the HR on my Fitbit because I was curious as to what it was at that time and ended up looking back at a few months. All of them my “fertile window” (Although of birth control so my lining was too thin for the egg to implant) was around the 8th They all spiked then and then went down. I went off birth control this month (bottom right chart) My natural cycle is a little longer than 28 days so I think that’s why it spiked a little later than the other months, but this month it spiked but didn’t go back down. I know it’s not a for sure indicator but wanted to get others thoughts