Pregnant 6+3, and Heart Rate

Hello-
I've had two consecutive miscarriages within the last year, finally pregnant again- but of course having a miscarriage takes away from so much of the joy and adds so many questions and things to worry about.  I wear a Fitbit and typically my resting heart rate before pregnancy is around 53-55, it has jumped up to 62, but leveled out at 61 for two weeks now.  Today it is all the way down to 58... anyone else have some experience with this?  I'm 6 weeks, 3 days along and just so ready for a turn to be a mom! Thanks for any advice, good or bad.