Resting HR Dropping 6w4d-6w6d

Stacia
Hey all, is anyone monitoring their resting HR with a fitbit?? I loved watching my resting HR rise in the last couple weeks but now it is dropping fast and it's making me nervous. Although the day it started dropping was the day of my ultrasound and the little babe was doing perfectly. My regular HR during the day is still elevated. I just don't know if I should be concerned or not.